One of the main changes that this standard has implemented is the removal of secondary interlocking. Over-rides, fan bypasses or secondary interlocking of any form are not allowed and the design of any fitted interlock system should be so that an override is not included.

It is important that the interlock and ventilation scheme has been designed to ensure adequate ventilation levels are met and that Gas Safety (Installation and Use) Regulations 1998 (GSIUR) are being followed.

This statutory document states:
“Regulation 27(4) No person shall install a power-operated flue system for a gas appliance unless it safely prevents the operation of the appliance if the draught fails.”
As a mandatory document, this takes precedent over UP19.

UP19 also provides further support for the monitoring of CO₂ levels to determine adequate ventilation levels are met and the potential for controlling the mechanical ventilation above the set minimum.

For newly designed kitchens the CO₂ level within the staff working areas of the kitchen should be below 2,800 ppm and that the gas should be isolated if the CO₂ level rises above this limit. For existing installations where a 5,000 ppm limit is reached the kitchen gas supply will be isolated until the CO₂ reduces.

Only CO₂ detectors that have been designed for the arduous conditions of a commercial kitchen should be used, with features such as a PTFE filter that can be easily changed periodically being considered. Although commercial and industrial CO₂ detector heads will make some allowance for unclean air they could eventually become blind in the air of a commercial kitchen.

Please don’t hesitate to contact us to discuss the location and mounting of CO₂ detectors in a commercial kitchen. See also these two other standards British Standard 6173/2009 and IGEM/UP2, Edition 2, which will help you.

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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This is a comprehensive document that, in our opinion, has paid much consideration to common sense though some of the descriptions and terms used are outdated. Below are some relevant extracts. Please call or email for more information should you require it.

Laboratory Gas Control
The document states under 6.2.4.1 that:
“Where an AIV (gas solenoid valve) is required the system shall include a downstream integrity check before the valve can be reopened.”

“Downstream integrity check” means gas pressure proving system.

The term “Where required” is explained in 6.2.3 where it says that “where it is not practicable to install a manual quarter turn valve in a readily accessible position, or where it is required to interlock the gas supply with other safety systems such as air flow, fire or gas detection an automatic means of isolation shall be installed.”

The term “automatic means of isolation” is explained in 6.2.4 where it describes the term as meaning a gas pressure proving system. In relation to the use of gas pressure proving the IGEM documents UP/1A, Edition 2 and UP2, Edition 2 give more advice on the utilisation of proving for safety.

Food Technology
Section 11.2.4. states that “mechanical ventilation or extract systems shall be interlocked”.
Also, 11.2.4 goes on to say:
Note. Must be read in conjunction with 11.2.5 and accompanying note.
“Where the ventilation requirements for new installations cannot be met, CO₂ monitoring shall be fitted. It shall provide an alarm condition at not more than 2,800 ppm to warn the teaching staff to increase ventilation and an automatic shut down of the gas supply at 5,000 ppm.”

Section 11.2.5 is clear in stating that:
“Means shall be provided to monitor the correct provision of air supplies, for example by airflow monitoring by air flow switches or by fan power monitoring. Failure shall lead to the shut down of the gas supply to the cookers.”

“Air supplies” also means extract and “fan power monitoring” means current monitoring in modern terms. As part of the interlock control a gas pressure proving system should be incorporated. For further information see ‘Medem’s news article entitled Individual laboratory control.

Gas Detection & Carbon Monoxide Monitoring in Classrooms
6.2.5.5 and 6.2.5.6, in essence, it requires that where a boiler room is connected to a teaching area then CO monitoring should also be installed in the occupied area. Consideration should also be given to installing combustible gas detectors within the same teaching area.

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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