Seo Google Safety : Calibration Basic|Information|Safety|Tips

Introduction

It is quite unlikely that you will ever use an absolute method for gas detection. Rather, you will employ any one of dozens of “relative” [or “reference,” but not necessarily EPA Reference] methods—that is, methods that produce some output that must be calibrated against a known standard. Then, its display can be directly read out in units of concentration, usually parts-per-million (ppm).

Even though proper calibration is 90% of successful gas detection, it is a subject that has been neglected—often purposely—by the majority of instrument manufacturers. There’s a good reason for this, of course: Proper calibration can often be difficult and expensive. But, we’re getting a bit ahead of ourselves.
Gas Blends in Cylinders

Early occupational health toxic gas detection focused on carbon monoxide (CO) and hydrogen sulfide (H2S). The calibration standards were supplied as gas blends in cylinders, and in the case of CO, at least, things worked out pretty well. This is because CO is not very reactive, and, within reason, maintains a stable concentration in the cylinder, as the pressure drops with use.

On the other hand, H2S is very reactive, and the original simplistic techniques used to create the cylinder gas blends could not provide a stable product. The problems observed with H2S blends were soon seen in blends for many other toxics. To make matters worse, improper analogies were drawn between experiences in combustible gas detection and toxic gas detection, establishing a false sense of security about poorly prepared gas blends.

In fact, other than the obvious point that both combustible and toxic gas detection get involved with detecting gases, the two fields of endeavor could not be more different.

The combustible gases of interest are nearly all stable (unless they are ignited by some external source), while nearly all toxic gases are unstable, and in many cases are extremely reactive. Most importantly, though, combustible gas detection is done in percent level concentrations, while toxic gas detection is done in parts-per-million, and even parts-per-billion concentrations—10,000 and 10 million times lower, respectively!

Fortunately, calibration gas blending technology has improved, encompassing specialized techniques for passivating the cylinders, as well as logging experience to determine how long a blend must age to become stable, and how long stability can be guaranteed. Much of the technological development has been done with aluminum cylinders, since this material seems to be less prone to wall effects and unwanted chemical reactions than steel.

Interscan can recommend good gas blend suppliers, but no matter what company you choose, the following points are important:

Order the blend so that the concentration is about 50% of the instrument’s measuring range.Ensure that the blend’s analysis is ± 2% accurate (or better).Insist on NIST–traceability.Obtain a written guarantee as to how long the blend will be stable.Since most of the cost of the blend is in the analysis labor, order the largest cylinder you can use. Stay away from disposable cylinders, which just become a solid waste problem. After all, we ARE in the environmental business!Before you order, ask for references for the exact blend, or one that is similar, and check them.

Permeation Devices

Some material courtesy of VICI Metronics

Certain toxic gases are not well-suited to being stored in cylinders, and cylinder blends are cumbersome to re-standardize, in that a separate (usually wet chemical) analytical method is required. In addition, some instrument users need a source for several different calibration standards. These situations call for permeation devices.

Permeation devices are small, inert capsules containing a pure chemical compound in a two phase equilibrium between its gas phase and its liquid or solid phase. At a constant temperature, the device emits the compound through its permeable portion at a constant rate. This rate can always be determined via differential weighing at constant temperature. Permeation devices are typically inserted into a carrier flow to generate test atmospheres for calibrating gas analyzer systems.

These devices are discussed in some detail in our Tech Center. Typical applications for Interscan analyzers include calibration for bromine, chlorine, formaldehyde, hydrazine, hydrogen bromide, and hydrogen chloride. Many Interscan customers who do not wish to perform their own permeation device calibration—although it is always recommended to calibrate on site—can take advantage of our Electronic Calibration Service (ECS).

Note that having calibration facilities on site provides the best possible answer to the question “How do I know that this monitoring system actually works?” You can challenge the system with a known concentration of gas at any time.
Zero Gas

As you can imagine, if your measurement range is in the low ppm (or less), accurately zeroing the instrument is of vital importance. Consider that it is not a trivial matter to remove contaminants such as carbon monoxide from air below tenths of a ppm.

Zero air can be obtained from the same vendors who manufacture gas blends. We would make the following recommendations:

• Tell your supplier your target gas and measuring range, and have him suggest the proper zero gas for your application.
• Ask for a written analysis of the zero gas. Ideally, there will be specific information and not just a series of “less thans.”
• As we noted for your calibration gas, before you order, ask for references for applications as close as possible to your own, and check them.

Hard Cases

There are compounds that will present challenges. Hydrazine, for example, done correctly, requires an expensive and elaborate set-up, and a skilled operator. Chlorine dioxide is unstable, and although in situ calibration methods are available, great care is required to produce accurate results. Known concentrations of ozone can be generated, but it is not cheap.
How Frequently Should You Calibrate?

In general, the lower your measuring range, and the greater accuracy you desire, then the more frequently you should calibrate. Calibration monthly is a good median recommendation, and bi-monthly is even better. When we say “calibration,” we mean a good patient effort, that allows for sensor and instrument stabilization, to get a good, solid, reproducible reading. So-called bump tests, that challenge the instrument with some unknown, but high concentration of gas prove little, and can often be misleading. For the most part, these are NOT recommended.

In certain cases, less frequent calibration will still afford satisfactory results. Feel free to discuss this at any time with our service department.
In Conclusion…

The bad news is that calibration for some chemicals can be difficult, yet it is essential for proper gas detection. The good news is that we are here to help.

Goggle safety Education : Safety Device / How To select Gas Detectors / Safety Goggles/ safety

Gas detectors have been around for a long time, starting with that infamous methane sniffing canary, which sadly was a one-shot device, which when subjected to methane, tended to die rather quickly with no audio and visual alarm capabilities other than a slight cheep and a total lack of motion. Fortunately technology has advanced significantly and we find ourselves at this point in time with some very sophisticated electronic equipment. But even the most sophisticated technology is useless if the sensors used are unable to detect the gases present. The three main atmospheric hazards that you test for prior to and throughout a confined space entry are:

Combustibles (Flammables)
Eg: Methane

• Propane
• Gasoline
• Various other site-specific hydrocarbons (specific to your industry)

Oxygen – Deficiency and enrichment

Toxics
Eg: Hydrogen Sulfide

• Carbon Monoxide
• Toxic Hydrocarbons
• Various other site-specific toxics (specific to your industry)

Depending on its sensor configuration, proper gas detection equipment can help identify the hazard
and protect your workers. Selecting a gas detector should be based on the hazard faced. Unfortunately far too many purchasers make one of the largest and most crucial single equipment expenditures without really understanding what they are buying. Sensors and their capabilities are the single most important factor when choosing a gas detector, yet more often than not, decisions are based on size,
price, bells and whistles and other such features that have nothing to do with the instrument’s detecting abilities. Gas detectors come in a variety of sizes, shapes, colours and sensor configurations. For confined space work, it is necessary to monitor for oxygen deficiency/enrichment, combustible gases and toxics. Therefore an instrument capable of dealing with these three hazards is necessary.

SENSOR TECHNOLOGY
Combustible Gas Sensors
a) Catalytic Combustible Gas Sensors.
These sensors look for explosive atmospheres. They detect combustible gases by causing an actual
combustion of gases within the sensor chamber. Catalytic sensors offer good linearity, and can react to most combustible gases. However, as resistance change to %LEL is quite small, they work better in concentrations between 1,000 and 50,000 PPM. They do not measure trace amounts of gas (under 200 PPM) and therefore are of no use in determining toxic levels. The disadvantages are:

• They must have a minimum of 14% oxygen content in the air to work accurately the sensor can be damaged by lead or silicone or other catalytic poisons
• the readings can be affected by humidity and water vapour condensation they respond poorly to low energy hydrocarbons such as oil vapours, kerosene, diesel fuel and commercial
• jet fuels
• they tend to loose their linearity after a year or so
• they are not recommended for use in an acetylene atmosphere

The flame arrestor will prevent ignition of most gases except acetylene outside the sensor. It is extremely important to check the approvals for which type of hazardous locations the detector can function in. Most portable gas detectors today will be certified for service is Class I, Div I, Group ABCD atmospheres.

b) Metallic Oxide Semiconductor (MOS) Combustible Gas Sensor MOS or “Solid State” Combustible Gas Sensors have been around for years. This sensor has a long operation life (3 to 5 years), is very rugged and will recover better from high concentrations of a gas that could damage other types of sensors. There are also disadvantages:

• MOS sensors also require oxygen to work accurately, although not as much as the catalytic
• some sensor’s heating elements have a high demand for power which requires larger battery packs
• the readings can be affected by humidity and water vapour condensation
• the MOS sensor may respond to many VOCs, HFCs and solvents, but is not specific to any single compound.

c) Infra-Red Combustible Sensors
Recently Infra-Red Sensors have begun appearing in some instruments. They work well in low oxygen levels or acetylene atmospheres; however, they are quite expensive. These sensors work by reflecting light off a mirror and measuring the amount of light adsorbed during refraction. Infrared sensors typically require a constant flow across the sensing assembly and may be slow to clear from alarm. They are unable to detect hydrogen. An Infra-Red sensor calibrated for a simple hydrocarbon such as Methane or Ethane will not be accurate for vapour of higher molecular weight hydrocarbons, solvents or fuels.

Toxic Sensors
a) Electrochemical (Wet Chem) Toxic Sensors
These sensors react to a specific chemical (substance). Chemically specific sensors are available for up to 30 different gases including chlorine, ammonia, carbon monoxide, carbon dioxide, nitrogen dioxide, nitric oxide, hydrogen cyanide, hydrogen sulfide and sulfur dioxide. The manufacturer’s technical information will indicate what sensors are available for their unit.

4 SENSOR PORTABLE
COMB, H2S, CO, O2
These sensors have very good linearity, which makes them very accurate for the substance they will react to. They can measure either large or small quantities and these sensors have a typical life span  of approximately 1 year for many toxic gases and up to two years for hydrogen sulfide and carbon monoxide. As with all sensors, Wet Chem sensors have their limitations. The electrolytic fluid can freeze when left in environments having temperatures lower than 0 degrees C. Some chemical sensors may be adversely affected by altitude as they may be pressure sensitive. Abnormal readings are another issue with regards to Wet Chem sensors. Abnormal readings are generally readings that don’t make sense. For instance you are working in a sanitary sewer and your instrument is showing a CO reading of 300 PPM (current TWA in Ontario is 35 PPM) and a low reading (below the TWA of 10 PPM) of hydrogen sulfide. What you likely have is an interference from the hydrogen sulfide. Some electrochemical carbon monoxide sensors are subject to interference from low levels of  hydrogen sulfide. The knowledge that carbon monoxide is not a common occurrence in sanitary sewer applications (whereas hydrogen sulfide is) would lead you to consider that you are probably having an interference problem. In some instances, oxidizers like chlorine, chlorine dioxide and ozone can cause opposite readings on such toxic sensors such as carbon monoxide and hydrogen sulfide. Awareness of the hazards in your workplace, some basic understanding of chemistry, knowing what interfering gases adversely affect your unit and strict testing protocols will minimize this problem.


b) Metallic Oxide Semiconductor (MOS) Toxic Broad Range Gas Sensors
There are a number of different MOS sensors on the market and one has been developed for detecting toxic gases. Its make-up and operation is similar to the one used for the detection of combustible gases. However, the MOS broad range toxic sensor is capable of reacting to low PPM levels of wide range of toxic gases including carbon monoxide, hydrogen sulfide, ammonia, styrene, toluene, gasoline and many other hydrocarbons and solvents. MOS sensors cannot detect carbon dioxide or sulfur dioxide. The sensor is incapable of telling you what gas you have encountered or the concentration, only that the atmosphere may be hazardous to your health.

C) Photo Ionization Detectors (PID’s)
Industrial Hygienists, Safety and Environmental professionals and others have used Photo ionization sensor technology for evaluating atmospheric hazards in the workplace since the 1960’s. Life expectancy of these sensors is 1-3 years and costs range between $300 and $1400 for lamp replacement. They are usually too costly to use in a multi-sensor instrument. Oxygen Sensors
Oxygen sensors are the only true chemically-specific sensors. They are similar to the electrochemical (Wet Chem) sensors described previously. They are also susceptible to freezing, are sometimes  affected by altitude and have a nominal operational life of one to two years. Never use an oxygen sensor to detect toxic gases. It is true that a toxic gas will displace the oxygen in a confined space. However, it takes 60,000 PPM of any gas to lower the oxygen from 20.9% (normal) to 19.5% (alarm point). More importantly, 60,000 PPM of any toxic gas will kill you.

DESIGNING A GAS DETECTOR
Let’s build a gas detector for confined space work. To start out it will require a combustible sensor. We previously described the three types of combustible sensors available and their features. However, for confined space work, any of the three technologies will provide adequate protection. Secondly, we need an oxygen sensor to detect both oxygen enrichment and deficiency. There are several manufacturers of oxygen sensors and while they may all look different, they are essentially the same technology and will work well. To complete this instrument we will require a toxic sensor(s). The key to safe confined space gas detection lies in these toxic sensors. There are two main sensor types used in multi-sensor instrmuments electrochemical (Wet Chem) and Broad Range (Solid State MOS).
To select the correct toxic sensor we need to evaluate our confined spaces. If your area of work is an industrial site, where the toxic gases are known or can be controlled, then a chemically specific toxic sensor can be chosen (providing a sensor exists for that gas hazard). Manufacturers produce gas detectors that are capable of supporting one or two of these chemically specific sensors. Some instruments are available with a range of plug-in sensors that can be changed in the field without fuss or calibration. Other instruments must be ordered with the specific toxic sensor(s) you require. However, there is a limit to the sensors available and, if toxic hydrocarbons or solvents are a concern (common to municipal water and waste water systems as well as industrial applications), then the broad range (MOS) type may be your best bet. If you are in an area where the toxics are unknown or cannot be controlled, such as storm and sanitary sewers, pumping stations, waste treatment plants, industrial sites with toxic hydrocarbons and the like, then the broad range (MOS) type is your best solution. Unlike the chemically specific electrochemical sensors, these sensors cannot differentiate one toxic gas from another but they will tell you whether it is safe to enter or it is time to get out. The broad range sensors have their limitations as well and cannot detect any of the dioxides, i.e.:
carbon dioxide, sulphur dioxide. It must be noted that a gas detector with a combustible sensor
will not protect you from toxic levels of hydrocarbons. A classic example is gasoline. Gasoline used to have a TWA of 900 PPM. It is now considered a carcinogen. A combustible gas detector, calibrated to methane, will not alarm on gasoline until around 50% of the LEL or 5000 to 7000 PPM. This is well in excess of the old TWA and is certainly an
even bigger problem now that it is rated as a carcinogen. Regardless of its cancer causing issues, this level can cause a worker to be rendered unconscious, potentially causing death through drowning or falling. The only toxic sensors capable of detecting these low levels of hydrocarbons are the broad  range.


SAMPLING METHODS
In confined space testing it is important that the operator know how the sensor comes in contact (operation) with the atmosphere. There are three primary means of exposing the sensor to the  atmospheresample draw, diffusion and a detachable remote diffusion sensor assembly. There are strengths and weakness in all systems. Selection should be based upon need, not availability. Sample Draw The most common form of sampling a confined space is the sample draw method. The  advantage of this method is that any monitoring is performed outside the space. With a sample draw system, a pump moves the sample from the atmosphere and draws it through a hollow tube to the sensor. The pump can either be a “bulb” hand aspirator which requires squeezing or an internal motorized sample pump. Drawing the sample to the detector protects the tester by eliminating the need to enter the space and limits any movement of the door/cover to the space that may create a spark, which could ignite flammable gases that may collect around the entry point. For these reasons, the sample draw method is recommended when conducting your pre-entry test. The primary  disadvantage of this method is sample dilution. The tube leaking or using a tube over 12’ in length may reduce the concentration of some contaminant to the point where the readings presented are inaccurate. Other problems may include leaking pumps, cumbersome sample lines, and in some environments, the sample line may plug due to sludge, dirt or condensate icing. A disadvantage of the manual sample draw methods is the effort involved moving the air sample along the tube to the sensor. A general rule of thumb is that it takes 3 pump strokes to move the sample 1 foot. If your line is 12’, it will take 36 pump strokes to get the sample to the sensor, then the sampling must continue for up to 3 minutes to ensure a proper undiluted sample. If you are using a bulb hand aspirator strong
wrists are both a requirement and the end result of a lot of entries.


Sensor Operation

5 SENSOR PORTABLE
O2, COMB, H2S, CO, MOS TOXIC
Most gas detector sensors operate by diffusion. Diffusion works by air being absorbed into the sensor
cell. Electronic gas detectors rely heavily on diffusion sampling. The atmosphere must be brought to the gas sensors by the aforementioned sample draw (aspiration) or by lowering the gas detector into atmosphere. Some manufacturers offer a detachable remote sensor assembly as a means of remote sampling. Advantages of this technology include the lack of pumps and moving parts, much faster response time than aspiration and wires can carry the information with no potential of diluted readings. The sample method is still diffusion but the sensors are lowered into the atmosphere to be tested. Once the atmosphere has been tested by aspiration and/or remote sensors, the gas detector can be worn by the worker for the duration. Because each sampling method has its own strengths and weaknesses, all techniques are used to monitor the atmosphere. The sample draw is used for the pre-entry test that occurs just inside the space at the doorway. (suggestion: use a 6’ or shorter tube). Diffusion sampling occurs at all other times. Regardless of sampling techniques, spaces two to three meters deep should be tested top and bottom before entering. Spaces four to five meters deep should be tested top, middle and bottom before entering. Calibration/Bump Test All portable gas detectors should be calibrated according to the manufacturers recommendations. Not calibrating or bump testing a gas detector on a regular basis is an invitation to disaster. Sensors and/or electronics can, and do fail and it is only prudent to check your instrument on a regular basis.
a) Bump Test
A bump or field test is the application of a known gas concentration in excess of the calibrated alarm
point of the instrument. When this gas is applied to the gas detector it should trip the alarm point ensuring that the instrument is functioning correctly. If it does not then it indicates that a re-calibration is necessary. Multiple gas mixtures are available that allow you to do a simultaneous Bump test with one canister of gas. It is a good policy to bump test at least once a week.
b) Calibration
Calibration should be performed as per the manufacturers recommendations. Calibration is done with
a known gas concentration that can be at the exact alarm point or at a higher concentration where the set point can be adjusted. This varies between manufacturers. If you are Bump/Field testing on a regular basis you can wait until that tests indicates a re-calibration is required. If Bump/Field test are not performed then the unit should be re-calibrated on a regular basis. Manufacturer’s recommendations vary from daily to never. Daily may not be practical and never, while time saving can be an invitation to disaster. Somewhere in between is the answer. Every three to six months is common.

DESIGN CHARACTERISTICS
The third component to consider in gas detector selection is design characteristics. Many gas detectors are sold solely upon these characteristics. The reason for this is that many gas detector manufacturers do not make their own sensors. They design and make the electronic box of the gas detector. The following characteristics should be considered after selecting the appropriate sensors:

• Construction
• Electronics
• Approvals
• Ease of use

a) Construction
Monitoring devices must be very rugged and easily carried by the workers. Even with training and the best intentions of the workers, field use does abuse the units. Drops, jolts, exposure to the elements, misuse, etc., all can shorten the life of the instrument. The case and its components must be constructed to withstand rough handling. The unit’s alarm systems, which should be both audio and visual, must be loud enough to be heard in your environment by either the attendant outside the space or the entrant(s) inside. In a perfect world, both attendant and entrant would hear the alarm. Some manufacturers have remote alarms that could enable both the attendant and entrant to simultaneously hear the alarm. The option is only worth the money spent if the remote wiring is long enough for all your spaces. Batteries are another consideration. Batteries can be either disposable or rechargeable but either type should supply enough power to last 10 to 12 hours. If the batteries cannot last the entire work period, a back up or stand by power source must be present. Batteries have all sorts of limitations. Many units have no way to determine the charge in them; cold and age decrease battery life; lead acid batteries can leak and damage your electronics; NiCad (rechargeable batteries) can develop memories and so on. Battery maintenance costs and efforts should be evaluated very carefully to ensure your system will work when required. The new nickel metal hydride rechargeable batteries appear to have cut down the memory problems found in the older NiCad rechargeable  batteries. For confined space work, gas detectors need to be portable (hand held). If the unit is  designed to be worn by the worker, it should rest on their belt, not weigh it down. In many tight spots, the worker should not wear the device as it may create a catch point. It may be advisable to have the ability to hang up the unit inside the space. Switches, buttons and knobs should be positioned or designed so that they cannot be knocked out of position, but one can still operate them with gloves on. The unit should be tamper resistant and default to an alarm mode in the event of battery or sensor failure. Gauges and/or displays should be large and easily read and understood. This means you must be able to not only see the displayed data, but also understand it. In confined spaces there are all types of lighting. Does the information show in all lighting situations? And finally, do the abbreviations make sense or do you need an explanation card on the detector? If the information cannot be understood, it may not be performing the job that it is intended to do.

b) Electronics
Information provided must be reliable and useful as life and death decisions can be made based on the data provided. The electronics’ response time, accuracy, precision, radio frequency (RF) interference, reading drift and sensitivity are all factors that can differentiate a poor purchase from a good investment.

c) Approvals*
Once a manufacturer has developed an instrument for use in a hazardous atmosphere, it should be approved by an independent laboratory for intrinsic safety. Ie: UL, FM, CSA, TUV, MET etc. Federal OSHA in the USA identifies such approval laboratories as “NRTL” (Nationally Recognized Testing Laboratories) and lists four pages of them on its website.

d) Ease of Use
One of the most important considerations after sensor evaluation and selection is the ease of use of the instrument. Is it simple to operate? Is it simple to understand? Are the buttons/switches easy to use with gloves on? Do you have to use switches or buttons to get alarm information? Will it alarm when battery/sensors fail? Most importantly, is it one switch operation?

TECHNICAL CONSIDERATIONS
RF Protection
Radio Frequency Interference (RFI) protection is the unit’s ability to protect the readings from interference caused by radio waves, pulsed power lines, transformers, and generators. RF protection is expressed in immunity to x watts of radio transmission at a specific distance. A prudent consumer should test a gas detector in and around cell phones, radios and walkie talkies before purchasing, especially if the gas detector is packaged in anything other than metal.

Response Time
4 SENSOR PORTABLE
COMB, O2 AND ANY 2 OF 13
FIELD INTERCHANGEABLE
TOXIC SENSORS

This is the time period between obtaining data from the sensors and displaying it. This time period
depends on what information is collected, the sensor response, how the unit of measurement being used (e.g. % LEL or PPM). Response time can range from several seconds for catalytic elements to minutes for some toxic sensors. Accuracy and Precision Accuracy is the relationship between the readout and the true concentration. This relationship is indicated by an error factor (indicated by “+/-“,e.g. +/- 0.5%). The lower the number, the greater the instrument’s accuracy. Precision is the number of times the accuracy would be right in any given number of tests (correct 19 times out of 20). In this case the higher the number, the greater the precision.


Sensitivity
This is the unit’s ability to accurately measure changes in concentrations. The hazards presented by
the substance being measured would determine the need for sensitivity. For instance, at present in Ontario, chlorine has a time weighted average exposure value of 1 PPM and if is IDLH at 10 PPM; therefore, any change must be noted at once. On the other hand, carbon dioxide’s TWAEV is 5000 PPM, and is IDLH at 40,000 PPM; therefore the sensitivity need not be that great.
Selectivity/Specificity This is the ability of the sensor/circuitry to respond to the desired target gas to the exclusion of other interfering gas species.


Reading Drifts
This is the movement in the instrument’s electronic readout when the atmospheric value remains the
same. Moving the instrument from one angle to another, shaking it, ambient vibrations or no apparent reason may cause the readout to change. Poor electronic circuit board design and/or age of the machine or the sensor will cause the readings to drift. Sensor or component aging causing this problem is acceptable and can be compensated for as part of the unit’s ongoing maintenance program; however, poor construction is not acceptable. Poor construction cannot be repaired and creates mistrust of the unit with those who work with it. If they do not trust the readings, they will not use it and a tragedy could easily occur. Your best protection is to contact current users of the instrument and ask about their experiences. Well we have now arrived at close to 4100 words on selecting a gas detector. If you are still awake, congratulations, because to get to this point you must have some interest in this topic not to have been bored to death. In closing I would like you to please keep in mind that portable gas detectors are available from a variety of manufacturers. They range from single electrochemical sensor instruments to very precise multiple sensor units. Do not be swayed by sophisticated technology and fancy packaging. Choose a device that meets your needs (both short term and for the next 3 to 5 years if possible). Look at all the variables from sensors to design, but always keep sensors as your number one criteria. Your employees also have to be considered in the equation. If not, a perfectly good gas detector will collect dust because they feel the damn thing isn’t any good! A well thought out purchase can save lives and prevent injuries

Seo Safety : Goggle Safety : Information : Typical Bulk Liquid Storage System

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Liquefied oxygen, nitrogen, argon, and carbon dioxide are stored on your site at very low temperature. When gas is required, the liquid is vaporized for supply to your process. For cryogenic applications such as food freezing that require a low-temperature liquid supply, the liquid is delivered from the storage tank to your process by an insulated line.

A typical installation normally consists of a tank, a vaporizer, and controls. Systems are selected based on your volume, desired pressure, purity level, flow rate, and operating pattern.

 Typical Liquid Storage System Used for Argon, Nitrogen, and Oxygen

A typical liquid storage system used for argon, nitrogen, and oxygen.

Tanks
The storage vessels generally used for liquefied argon, nitrogen, and oxygen are 500-, 1,500-, 3,000-, 6,000-, 9,000-, and 11,000-gallon tanks. Liquid hydrogen storage vessels are nominally 1,500-, 4,500-, 9,000-, and 20,000-gallon tanks.

Typical Tank Cutaway

Cutaway of a typical tank.

Ambient Air Vaporizer
While steam and electric vaporizers are occasionally used, the most widely employed vaporizers obtain heat from the surrounding air. These "ambient air" vaporizers are provided in arrays of many-finned tubes to provide vaporization rates up to 40,000 scfh per array. Additional units are added to provide higher vaporization rates.

Control Manifold
Control manifolds are designed to control the pressure to your houseline and to protect that line from excessively cold gas or possible liquid carryover. The manifold consists of a temperature control valve and a pressure control valve. Also included are necessary block-and-bypass valves, as well as a pressure indicator and check valve. There are two basic units—one for rates up to approximately 23,000 scfh and another for rates up to approximately 43,000 scfh.

 Typical Control Manifold

A typical control manifold.

*Note that the liquid storage system used in your region may be different; please check with your local office.

Seo Safety Oil & Gas :: Air Shut-Off Safety Devices for Diesel Engines

GE designs and manufactures the Rigsaver® air shut-off safety device for use on both large and small diesel engines. When mounted in the air intake system, the Rigsaver will prohibit airflow from entering the cylinders and positively immobilize the engine, safeguarding personnel, equipment, and the environment. Rigsavers can be manually or automatically controlled, responding to a variety of fault or hazard conditions.

It's not always regulatory but it is your responsibility to protect the environment, your equipment and, most importantly, your people.
Hazard prevention with air shut-off safety devices

Airborne hydrocarbons are dangerous. In the open, they can easily ignite and spread to available fuel sources to produce an uncontrolled inferno. But they can also pose a threat to diesel engines of any size. When mixed with the air supply, these vapors or fumes may be drawn into the air intake system, act as an ungoverned fuel source and cause the engine to accelerate out of control.

Conventional shutdown methods (i.e. shutting off the engine's fuel supply) are often ineffective in preventing diesel engine overspeeding since the ungoverned fuel source is still available through the air intake system. Completely shutting off the air supply, using a device such as the Rigsaver, is the only sure way to prevent engine runaway and the possible dire outcomes: equipment damage, fire, or life-threatening explosion.
Air shut-off valves for air intake systems

Rigsaver is a swing-gate, spring-operated air shut-off valve mounted in the air intake system. It will impede the airflow into the cylinders and positively stop the engine. It can be installed pre- or post-turbo. Rigsaver can be manually or automatically controlled to respond to a variety of fault or hazard conditions.
Worldwide experience with diesel engine shut-off valves

The Rigsaver air shut-off valve has been used worldwide, providing reliable service on and offshore under adverse conditions associated with locations in the Canadian Arctic, the Gulf of Mexico, the North Sea, the deserts of Africa, the Middle East and the Pacific Rim. Our product's quality meets or exceeds the stringent requirements of our broad customer base, which includes leading engine OEMs.
Features of the Rigsaver air shut-off safety device

Features of the Rigsaver air shut-off safety device include:

•     Manual or automatic controls
•     Can be used onshore and offshore
•     Can respond to a variety of fault or hazard conditions
•     Available with 2in (50mm) to 14in (355mm) of unrestricted port
•     Operates safely at ambient and induction air temperatures between +350°F to +400°F (+176°C to +205°C)
•     Meets ISO 9001:2008 requirements

Diesel emergency shut-down valve

The Rigsaver acts as an emergency shut-down valve for diesel engines. It is ideal for a wide range of applications, including:

•     Power generation
•     Bulk fuel loading facilities
•     Mining equipment
•     On/off - highway vehicles
•     Offshore platforms
•     Marine engine rooms
•     Petrochemical plants
•     Stationary equipment

Technical data of the Rigsaver air shut-off safety device

•     Temperature rating: maximum constant +400°F (+205°C); high temperature up to +482°F (+250°C) available upon request
•     Maximum pneumatic tripping pressure: 100 psi
•     Maximum solenoid energize time: 5 seconds
•     Vibration tested to simulate in-service conditions to ensure maximum durability and reliability
•     Manufactured with high-grade materials to protect against corrosion for extreme conditions such as oil and gas offshore
•     Available in bore sizes from 2in to 14in
•     Manufactured in Canada

Certifications

The Rigsaver is ISO 9001:2008 certified and is approved for use in hazardous zoned environments under ATEX Category II, Ex II 3G c T3 (200°C, industrial applications). (Note: This does not apply to electrical components.)


Source : GE OIL & GAS

Natural gas safety

Natural gas is a colorless, odorless gas until we add mercaptan, a rotten egg odor to help detect leaks. If you smell natural gas or have a natural gas emergency, and leave immediately

Safety tips

Natural gas is safe when properly used. Follow these tips to prevent accidents:

Never use your oven or range as a space heater.

Have a qualified contractor inspect your furnace, vents, connections and chimneys for corrosion and blockages at least every other year.

Keep the area around your furnace and water heater clean and free from litter. Clean or replace air filters in your heating system annually.

Keep chimney flues and appliance vents clean and in good repair.

Vent gas space heaters to outside. Never sleep in a room with an unvented gas or kerosene heater.

Make sure your range top is clean. Wash burners with water and mild detergent. Gas range flamed should be crisp, quiet and blue. Yellow flame indicates need for adjustment.

Make sure water heater air intakes, drain pipes, controls and flue are unobstructed.

Keep your gas meter free of debris, snow, ice and other obstructions at all times.

Natural Gas distribution network

Natural gas distribution networks are subject to rigorous inspection, maintenance and oversight within our company and by state and federal government. We maintain about 20,000 miles of natural gas distribution mains and 530 miles of natural gas transmission pipelines throughout Wisconsin. We also maintain the pipes that connect the mains to individual homes and businesses.

Typically, we are responsible for the natural gas facilities up to the outlet of your meter. Maintenance of additional buried natural gas pipes on your property is your responsibility. Examples include pipes to mobile homes, detached garages, workshops, pools, spas and lighting. According to federal rules, you are responsible to inspect buried piping on your property for leaks and corrosion. Any unsafe conditions must be repaired or removed.

Our inspection and safety activities

We survey for possible leaks on our distribution mains every year in populated communities and every other year in more rural areas. (Federal requirement for main surveys is once every five years).

All of the transmission pipelines are surveyed for leaks at least once per year. All of our 1 million customer service lines are inspected within every three years. (Federal requirement for service line surveys is once every five years). We have corrosion protection on all steel pipe in our system. (Federal requirement requires corrosion inspections only on pipes installed prior to 1971.)

Our corrosion protection is monitored continuously and tested every year. Wisconsin limits the operating pressure of a distribution system at 60 psig (pounds per square inch). (The Federal limit allows for distribution systems to operate at 125 psig.)

Along with inspecting the existing lines, we invest approximately $50 million every year in upgrading and proactively replacing mains and service lines throughout the area.

We work with local public safety agencies to provide emergency response training and safety information.

Each year, we sponsor contractor workshops to reinforce the proper safety guidelines for construction crews that work around natural gas and electric facilities.

For security reasons, we do not provide maps containing exact locations of pipelines. You can find the pipelines in your community by visiting the National Pipeline Mapping System. Every other year, we send out a communication to all customers within 1,000 feet of a transmission pipeline.

Pipeline damage

Most incidents involving natural gas pipelines involve a contractor or homeowner digging into buried distribution lines. To avoid such situations, be sure to call 811, a national hotline for underground facility location and marking — at least three days prior to digging. Using flags and paint, the free service marks any underground facilities that should be avoided when digging.

Dig safely

Dig by hand when excavating around natural gas piping. Contact an underground locating contractor for help locating natural gas piping on your property.

Contact a qualified plumbing or heating contractor, for help with natural gas piping inspection and repair.

Appliance connections

Make sure all appliance connectors are approved for the use expected, double wall and coated. Refer to the Consumer Product Safety Commission for information on approved connectors.

Corrugated stainless steel tubing

Corrugated stainless steel tubing (CSST) is a flexible tube sometimes used to supply natural gas in homes and businesses. Used since 1990, CSST may have been used for natural gas piping in your home if you added a new natural gas appliance such as a stove or furnace.

Danger: Improperly bonded and grounded CSST can result in natural gas leaks or fires in buildings struck by lightning. Learn about our CSST policy requirements (PDF 1688k). CSST is often coated in yellow or black. Photo

Do not confuse CSST with natural gas appliance flexible connectors. Flexible connectors typically attach directly to natural gas appliances from a floor or wall appliance shut-off valve. CSST is typically routed beneath, through or along side floor joists in the basement, inside interior wall cavities and on top of ceiling joists in attic spaces.

Inspect: If you have CSST installed at your home or business, contact a licensed electrician to verify proper bonding. If not, the electrician can install the proper bonding. If you’re not sure if you have CSST, contact the company that installed the natural gas piping in your home or business and ask for an inspection.

Fire Safety Clothings

Every tool firefighters bring to the scene of a fire is designed to withstand extreme heat, harsh chemicals, and dangerous conditions. This is true even of the clothes they wear. No material is completely fireproof, but firefighters’ clothes are designed to provide a fire-resistant shield that protects them against extremely high temperatures for a long period of time.

Firefighters’ clothes are typically made of a combination of Nomex—a material that provides extreme heat and fire protection, actually carbonizing in the presence of heat and creating a thick barrier that protects the skin—and Kevlar, a material that adds flexibility and breathability to allow firefighters to perform strenuous work even in difficult conditions. Here’s an overview of the gear firefighters wear when they respond to a call.

Fire kit. Also referred to as “turnout gear” or “bunker gear,” this refers to firefighters’ outer protective gear, which is highly fire resistant clothing. The term can be used to mean trousers, boots and jacket, or the entire system of protective clothing and equipment. According to tradition, the trousers and boots are traditionally stored by the firefighter’s bunk at the fire station for quick access. The trousers are typically stored crumpled around the boots so firefighters can step quickly into the boots and pull the trousers up.

Most fire brigades assign firefighters a jacket and trousers as part of their fire kit. This combination allows firefighters to take the jacket off if needed to cool off. Ordinarily, the fire kit’s job is to provide insulation from outside air—so they’re very hot.

Some fire brigades, however, assign a full-body suit that covers both upper and lower body. While this can’t be removed in situations where full-body protection isn’t needed, it also provides better protection from hot gasses, since there’s no gap between the top and bottom garments.

Boots. Firefighters use boots made of rubber or leather. They’re designed for extra toughness, fitted with safety toes and a midsole plate assuring puncture-resistance in case the firefighter steps on a nail or other sharp object. The rubber or leather is treated to be extremely fire resistant.

Helmets. A firefighter’s helmet is designed to protect the firefighter’s head from falling debris, as well as extreme heat. The helmet is made with a hard shell made to provide protection against heat, steam, electrical shocks and other hazards. Some come equipped with built-in goggles or visors to protect the eyes and face.

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Protective hoods. Helmets are designed for heat and hazard protection, but they don’t cover the ears, neck, and a significant part of the face. When full-body protection is needed, firefighters wear a hood that completely covers the areas not protected by the helmet. These are made from Nomex knit fabric—the same material that provides heat and fire protection on a firefighter’s fire kit and other fire resistant clothing.

The fire resistant clothing firefighters wear is designed to perform miracles. It allows firefighters to walk into burning buildings, rescue victims and extinguish fires without risk of serious injury or death. It can be very hot and heavy to wear, but the protection is worth it.