Download PDF of Dormont Installation Instructions

Download PDF of Dormont Gas Hose Codes

How do I know if the gas hose is supplying enough gas to the appliance?

The capacity of the gas hose (i.e. how much gas it can deliver) is measured in Btu (British Thermal Units). 3420 Btu = 1kw. There is no finite figure regarding how much gas (how many Btus) a gas hose will deliver, because the following factors will affect the individual installation:

•  Site gas pressure (could be high or low, or could even fluctuate.)

•  Gas type (could be Natural Gas or LPG)

•  Installation pipework layout (lots of bends and elbows will reduce gas flow)

•  Installation pipework size

•  Temperature

•  Humidity

•  Other appliances connected to the same supply

The installation engineer should carry out a pressure drop test to determine if the pressure drop is acceptable once the installation is complete.

In order to comply with BS669 part 2: 1997 (the British Standards applicable to commercial hoses), example Btu capacities are included in the Dormont gas hose installation instructions. (See Dormont Flexible Gas Hose Installation & Operating Instructions manual.) These are very conservative guideline figures only and assume several factors (.58 mbar pressure drop / 0.55 specific gravity gas etc.)

As a general rule of thumb - if the Btu requirement is equal to, or less than that shown in the table, the gas hose will be okay for that application.

LPG (liquefied petroleum gas) has a much higher heating value than natural gas and runs at a higher pressure, so if the requirement is marginally higher than that listed in the table, but the gas type is LPG, it will probably be okay.

Remember, the larger the bore of the hose, the greater the Btu capacity (because it will let more gas through.) The longer the length of the hose, the smaller the Btu capacity will be (because there is greater resistance for the gas to overcome before it gets to the appliance).

This is an important issue, because insufficient gas supply can cause dangerous emissions from the appliance.

If you are not sure, consider using a hose with a larger diameter or a shorter hose. If the connection on the appliance is too small for its Btu rating, consider using an adapter to facilitate a larger hose.

If still in doubt, contact a Corgi-certified engineer in the area to inspect the site.

NB: Corgi-certified engineers must only install commercial gas hoses.

Which British Standard are Dormont Gas Hoses manufactured to?

BS669 part 2: 1997. This is the certification to which all commercial gas hoses for catering applications must comply. In addition to the British Standard, Dormont also carries the following certifications: BS Kitemark Licence, KM 39643 and Corgi Technical Bulletin 54 - especially specific to the SwivelMax (Supr-Swivels).

What are 1st, 2nd, and 3rd gas families?

•  1st family gas is gas cracked from coal (Town Gas). This has largely been phased out now in favour of Natural Gas, but it is still used on the Isle of Man.

•  2nd family gas is Natural Gas.

•  3rd family gas is LPG (Liquid Petroleum Gas) this is usually Propane.

Dormont gas hoses are suitable for use with all three gas types.

Should the hoses have a red stripe down them if they are used with LPG?

No. Yellow is the colour specified in the British Standard for commercial-grade hoses. Black rubber hoses have a red stripe down them if they are used with LPG, but black rubber hoses are only acceptable for domestic installations.

I can't get any gas through my gas hose.

Each Dormont hose has a fusible link (also known as a Thermal Shut-Off feature) built into the quick-disconnect coupling or SafetyQuikT (formerly Cimfast) valve. The fusible link is a safety feature and is designed to shut off the gas if the coupling temperature gets to 350º F (177º C). Most likely, if temperatures have reached this level, there is a fire nearby and operation of gas-fuelled equipment would be quite dangerous. The unique Thermal Shut-Off feature is an added safeguard to ensure the safety of your premises. Contact Mechline to order a new coupling.

Sometimes, soldering or any installation work using flame or high heat in the immediate vicinity of the coupling can cause the fusible link to actuate. The installation instructions supplied with each hose specifically warn against this. If the fusible link has actuated, the coupling is rendered unusable, and a replacement coupling will need to be purchased.

Do I need a restrainer with my gas hose?

Yes. BS669 part 2: 1997 requires that a restraining device and hardware be supplied with each gas hose. If you prefer to not be supplied with a restrainer (possibly because you have your own), Mechline can still supply the product without the restrainer, however, the regulations to meet British standards would be compromised - as there is no way of knowing another restrainer is within compliance of BS669, part 2: 1997.

NB: Dormont provides two choices in Restrainers.

Code: RS - Straight Restrainer

Code: RC - Coiled Restrainer

The straight restrainer is the restrainer most often included with hose orders unless the Coiled Restrainer is specified.

Will Quick-Disconnect couplings for Dormont hoses fit other hoses?

Only Dormont hoses can fit Dormont Quick Disconnect couplings. The couplings will not fit on other hoses.

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