FAQ: Why choose Medem differential pressure proving?

FAQ: What is gas pressure proving?

Differential gas pressure proving is a method of performing a gas tightness test on downstream pipework, outlets, and appliances.

This is generally achieved by opening a gas isolation valve for a short period to pressurise the system and appliances, then closing the valve and monitoring for any drop in pressure. Any leaks in the pipework or appliances will cause a drop in pressure, preventing the gas valve from opening and triggering an alert. If there is no drop in pressure, the system will then open the gas valve, making gas available for use.

It is important to note that a gas pressure proving system can only identify a leak or open appliance/outlet during its test. Once complete, it cannot distinguish between a “gas leak” and “gas in use.”

Therefore, a gas pressure proving system must be switched off whenever the gas service is not in use, allowing the system to re-test for gas tightness at each service period.

FAQ: Why choose Medem differential pressure proving?

The differential gas pressure proving method as developed and patented by Medem operates by measuring the pressure differentially across the inlet and the outlet of a gas isolation valve using micro transducers. All other systems can only see the gas pressure when the valve is open.

1. Differential proving enables the supply pressure to be measured before the associated isolation valve is opened. This means that in the event of gas over pressure or under pressure the valve would remain safely shut and reported on the system LCD. Therefore only the differential gas pressure proving method can be considered to be truly fail safe.

2. This method is dynamic in that it takes into account any supply pressure changes that could be temporarily created by increased demand such as a boiler firing. Such transient changes in pressure would have the potential to cause other methods to isolate the gas supply needlessly.

3. Some other gas pressure proving methods can fail to identify a gas leak because they have to be set on installation and if the supply pressure at the time of setting is even slightly higher than in subsequent use then a leak can be missed during test.