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Bump Testing Options for Gas Detection Instruments

Bump testing gas detection instruments on a daily basis has become more and more common.

There are many reasons why bump testing is important.

The bottom line…it could save your life!

There are two definitions of bump testing (response testing) which are used in industrial and mining applications.

  • Apply gas mixture and observe whether the readings are increasing (toxics, combustible sensors) /decreasing (O2) and alarms come on. Typically less than 30 seconds. This confirms the instrument reacts to all gases and the instrument will alarm if required.

Or

  • Apply gas mixture and observe whether the readings are increasing/decreasing, alarms come on and readings reach a specific value relative to the calibration gas value. This value would be established as part of the company testing protocol. It could be a percentage difference than the calibration gas values or a specific value. This confirms the instrument reacts to all gases and the instrument will alarm if required.  It also determines the accuracy of the instrument in relation to the calibration gas value.

In either case, if the instrument does not react to the gas mixture and alarms are not initiated then the instrument must be calibrated by a competent individual or system.

How to Bump Test —- Show me the way

Today there are many ways to bump test a Gas Detection Instrument.

  1. Manual
  2. Bump Test Stations
  3. Automatic calibration or docking stations

In all cases a known concentration of calibration gas should be used with the correct gas mixture and concentration for the instrument type and your application. The gas concentration should be high enough or low enough (O2) to put the instrument into alarm. Alarm points should be checked to make sure they are set to the appropriate level for your application.

Manual:

The old ways are still used and provide the user with a quick and inexpensive way to bump test any instrument.

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A calibration gas cylinder, regulator, tubing and calibration cup for your instrument is all that is required.  

  • Turn on your instrument and allow it to stabilise.
  • Zero the instrument (if required) in clean breathing air or use a zero air mixture (never zero an instrument in a contaminated area
  • Connect the gas cylinder onto the regulator, connect the tubing and calibration cup to the instrument
  • Turn on the gas and let the gas flow onto the instrument
  • Observe the instrument as per your definition of bump testing
  • Turn off the gas and disconnect the instrument
  • The instrument is ready for use

There are different regulators which can assist in the manual calibration methods.

A standard fixed flow regulator or push button regulator would be used for diffusion instruments or an on demand flow regulator for internal pumped instruments.

Make sure you use the correct type of regulator for your instrument whether that is a diffusion or internal pumped instrument. For more on this see our blog Choosing the Correct Regulator for your Gas Calibration.

Efficiency improvements in manual bump testing.

When you have several instruments being bump tested regularly, it would be useful to evaluate the use of larger volume gas cylinders. These larger gas mixtures can improve the efficiency of your bump testing program, while decreasing costs. The larger the gas cylinder the lower the cost per litre. Using the gas calculator you can determine your annual gas volumes and then determine the size of cylinder which best meets your needs. (34-7500 litre cylinders are available). Both fixed flow and on demand flow regulators are available to connect directly to a high pressure/large volume cylinder. It performs the same task as using small disposable cylinders but you are saving money and time.

To increase the number of instruments you can test at the same time, add a gas panel inline which can have two, three or more outlets to allow you to test many instruments at the same time.

Bump Test Stations:

Today there are several bump test station which can be installed in the work area for quick and easy testing of your instrument. Some are mains powered and provide you the ability to set the flow rate and the length of time the gas flows. They are all one button operation which eliminates the need for extensive training programs on how to use the device.

The latest innovation is the pneumatic bump test station which runs off the calibration gas used. Simply bolt on the wall and connect your calibration cup and you can test two instruments at the same time. The benefit is you don’t have to worry about gas loss as the system turns off by itself and you can locate the station anywhere. No power/no batteries, means it can be in the work area available for testing your instruments at any time. Capable of being used with either disposable or large volume cylinders, these bump test stations take the “manual” out of manual testing.

Pneumatic bump test stations are extremely useful during shut downs/turnarounds when there are a large number of gas detection instruments being used. Having the bump testing station right in the work area saves time and money. Workers can check their instruments right then and don’t have to leave the work area.

A key element of most bump test stations is they are generic and can be used with any gas detection instrument. This provides real benefits for customers who have multiple types or brands of gas detectors

Automated Calibration Systems (Docking stations):

Over the past decade or more docking stations designed to automate the calibration and bump testing of gas detection instruments have become an important part of many customer’s gas detection programs.

Most gas detection manufacturers have a docking station of some type with varying capabilities. The core benefit is to have the gas detection instrument automatically calibrate and/or bump test based upon company criteria. This data is then recorded which can be used to evaluate company performance against standards or for regulatory documentation. Once the system is programmed with the devices and company calibration and bump test protocols, the system takes over.

Of course, you still need to have a worker put the instrument onto the system. This can often be the Achilles heel of the system because the location of the docking station can be some distance away from the actual work area. As all docking stations must be mains powered they cannot be in the hazard area which causes worker compliance to be an issue.

When used correctly docking stations can be an extremely beneficial tool.

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Whether companies use manual, bump test stations, docking stations or a combination of all three, bump testing is a critical part of any successful gas detection program. Without it gas detection devices could be used incorrectly in the workplace with potentially deadly consequences.

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