CAC-NRC Regulators…more options and uses than you may think

The typical application for bump testing or calibrating your instrument using an NRC regulators requires a fixed flow 0.5 liter/min regulator, a bit of tubing; a calibration cup; your gas mixture; and you are good to go.

There is nothing wrong with that, provided you are using the correct flow rate, regulator material and tubing. If your instrument has an internal pump, then you should be using the On-Demand Flow Regulator.

There are several regulators which can be used with NRC gas mixtures. Here are a few ideas for making your bump test or calibration system more efficient and functional.

Fixed Flow: FF-100

This is the most popular regulator as it has a fixed flow rate and a simple on/off knob. Make sure you do not mix and match regulators for different gas types. If you have instruments which are 4gas H2S/CO/CH4/O2 as well as instruments for chlorine or ammonia, never use the same regulator for more than one gas mixtures. Doing so has the potential to contaminate your gas mixtures. Small concentrations of H2S, for example, could be trapped in the regulator and once you connect that regulator to a chlorine cylinder the H2S can be drawn into the cylinder contaminating the chlorine mixture. Label each regulator for the gas type it is to be used for. Stainless steel is critical with chlorine, ammonia, hydrogen cyanide, nitrogen dioxide and other corrosive gas mixtures.

Variable Flow: VAF-100

Variable flow regulators have nine different flow rates from 0.5 to 5 litres per minute. They are ideal for technicians who may need to calibrate instruments with different flow rate requirements. A simple click of the dial will adjust the flow to your requirements.

Fixed system calibration often includes methane or H2S where the sensor is located high on a wall (CH4) or low in a sump (H2S). Delivering the gas mixture to the sensor may involve tapping into a permanent tube assembly running to the sensor head which may be several metres away.  Also, calibration cups for fixed systems are large which requires a sufficient volume of gas to test the sensor head. Using the Variable Flow Regulator (VAF) allows you to set the flow to 5 litres per minute to get the gas up or down to the sensor, then dial back the flow to the required rate, typically 0.5 l/min. This speeds up the process, reduces time, and gas volume.

Push Button: PBR-100

If you are concerned that operators might leave a fixed flow regulator on and drain a gas cylinder, then the PBR-100 is the answer. A push button on the top of the regulator creates the flow when depressed. Stop pushing and the flow stops. It can be used with gloves as well. The PBR-100 is a great option when you want bump test cylinders in the field for use by operators.

On-Demand Flow Regulator: ODFR-1001

This regulator is a must for all instruments which have internal pumps. Never use “T” pieces as the tubing is often cut back to the point where ambient air is being drawn into the “T” diluting the gas mixture. This can cause the instrument to have an incorrect reading or incorrect calibration. On-Demand Flow regulators have a 0.3-3 litre/minute range, for use with all gas detection instruments and many gas analysers which have internal pumps. The ODFR is also excellent for use with most docking stations that have internal pumps.

If you use the ODFR to deliver gas to multiple instruments or docking modules make sure you do not overload the 3 litre/minute capacity of the regulator. Always provide a safety factor of 0.5 l/min. One regulator can manage five instruments requiring 0.5 litres/minute.

Materials:

As already noted, do not forget stainless steel and Teflon lined tygon tubing for corrosive gases and ensure that you are using the correct tubing for your gas mixture.

 Manual/Automated bump test and calibration stations:

Gas Distribution Systems are great way to automate your calibration and test process. The GDS-100 provides many ways to improve efficiency and reduce cost.

For those who want to have a manual testing system you can still automate it with the GDS. Simply connect any one of the NRC regulators to the C10 connectors on the GDS panel in order to bump test and/or calibrate multiple instruments at the same time. You could have 2, 4, 6, 8, 10 or more outlets all connected to the same gas cylinder and calibrate that number of instruments at the same time. Fixed flow for diffusion instruments or On-Demand Flow for pumped instruments can all be used with the one GDS system.

Using the PBR-100, you can turn the GDS into a multiple instrument bump test station which can be located anywhere on the work site.  A great tool for shutdowns and turnarounds.

NRC regulators are not limited to simple calibration and bump testing of one instrument. They can be used in multiple ways and can be incorporated into automated systems for calibration and bump testing.

Contact us for more calibration and specialty gas solutions for a more efficient and safer workplace.

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