It is not common practice today to have an operative (caretaker) living on the site and therefore available to reset the boilers after a power cut, so the following section from the document is intended to overcome potential issues such as preventing pipes freezing. It also aims to minimise closures because the building has cooled after a power cut, perhaps the night before.

In section 3.1.8 boiler/plant rooms are covered by the following:
“School boiler/plant rooms are considered as areas of high fire risk. For this reason, the following fire safety precautions are required for new schools and where an existing boiler/plant room is upgraded or refurbished”

This section of the document then goes on to state that a boiler house attached to the main school building should be fitted with combustible gas and carbon monoxide detection. It also states that a pressure proving system can auto reset after a power cut so that the boilers can restart automatically.

Only the boilers for the heating of the school can have the gas supply on auto reset after a power cut.

If you require any additional information on our systems to help meet these design standards or wish to discuss the standards further please don’t hesitate to contact us.

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Section 2:
Scope 2.4 states that the document procedures apply in relation to the following (amongst others areas):
“Where there has been a complete loss of pressure for any reason, note, The closure of a valve, for example, the ECV, can result in the complete loss of pressure which necessitates tightness testing and purging before resumption of supply”

An explanation of the above in relation to gas pressure proving. The first referring to the words “can result in the complete loss of pressure”. When a solenoid or other type of ECV closes for whatever reason if a downstream boiler, appliance or Bunsen burner is switched on then the gas pressure will be lost.

This is likely to happen particularly where flame safety devices are fitted.

Further reasons for the use of gas pressure proving systems can be found in this standard IGEM/UP2, Edition 2.

If you require any additional information on our systems to help meet these design standards or wish to discuss the standards further please don’t hesitate to contact us.

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POTENTIAL HAZARDS
“A potential hazard could arise from the use of an AIV (valve) if it were to close and reopen without ensuring that any appliance installed downstream is isolated.”

“Under such circumstances, when the valve is re-opened, gas would escape from any appliance which had not been turned off (automatically or manually) thus creating a potential hazard.”

“A potential hazard is most likely to occur on a valve that restores itself automatically to an open position on removal of the fault which caused it to close.”

Examples of such an event are:

• a transient loss of electrical supplies (which can lead to significant operational problems).
• activation upon testing a fire alarm.
• a transient or intermittent fault of an interlock that actuates the valve.

It is argued that a boiler installation is a sealed installation and all appliances have flame safety devices fitted (FSD) so therefore proving is not required.

However, if you consider that flame safety devices can take up to 10 seconds to close after a valve has isolated the gas supply then the gas pressure between the closed valve and the burner can be reduced to 0 mbar. This would then require a tightness test before the supply could be restored.

Let us take the example of a fire system activation, emergency stop activation or power failure which deactivates a safety shut off valve controlling the gas supply to the boiler room.

After the test or activation, the control panel is reset and the gas supply is normally automatically re-established. The boilers are then relit and operated as normal. In most cases, the supply has been re-established successfully with no apparent hazard or risk. However, we must note, as indicated by the Health and Safety Executive and the gas industry in general, where we identify any risks which may create a hazard we should introduce control measures such to either alleviate or reduce these risks.

Gas pressure proving is used as a measure to confirm the integrity of the system either to negate any leakage or, if confirmed, warrant investigation and repair.

The installation of a gas proving system has many additional benefits the main one being that if the system is isolated as a result of a power failure, once power is resumed the system will automatically restart and perform a pressure prove, reducing the potential for site downtime or damage subsequent to pipes freezing.

Every year as part of an on-site DSEAR risk assessment for the plant room a leak test should be carried out of all the installed low-pressure pipework, an installed and correctly designed gas proving system can be used to complete this test. The system is simply switched off and back on again and the test completed, the alternative would be to call out a Gas safe engineer to complete the test and the subsequent costs associated.

If you require any additional information on our systems to help meet these design standards or wish to discuss the standards further please don’t hesitate to contact us.

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