Pilot Gas Valve Assembly

[som1973]

Hi Everyone,
We are Industrial oven manufacturers & we generally use Gas burner system with fuel gas trains having Main & Pilot gas lines.

We have some important questions regarding Pilot Gas train., see details below.

1. When do we need Pilot Gas Valve Assembly ?

2. Does EN746-2 standards or NFPA86-2015 Standards dictate the use of Pilot Gas Valve Assembly ??

3. Does the Pilot Gas Valve Assembly affects the Total price of the Gas burner system.??

4. Do we have any functional problems, when not using Pilot Gas Valve Assembly ??

Please review our questions & provide your valuable answers

Thanks

 

[SEP87]

I know this is a bit late, but as there are no replies i thought it might help.

The use of a pilot valve is usually dictated by the burner, i.e. if the burner requires a separate pilot inlet or a reduced startup flow rate. The burner manufacturer will specify when a pilot valve is required. There are generally two options; a) The pilot will bypass the main valves and then be piped back into the main line - there will be one burner head and ignition system which lights on a reduced rate. b) The pilot will bypass the main valves and then have its own burner head and ignition system (usually located near the main flame inlet).

I assume as you are manufacturing the ovens you are buying in the burners? If so you can only use a pilot if the burner is designed to work with a pilot, there may no be a separate pilot burner head or the main burner head might not be capable of keeping a pilot flame stable.

I don't believe EN 746 says you must use a pilot but it does dictate the allowable ignition times (safety times) for direct lighting and pilot lighting. There are two main reasons to use a pilot. Firstly on larger burners it is unwise to light on full flame because there will be a significant bang (more of a contained explosion) than a smooth light-up. This can very often cause significant damage to the burner, oven/chamber, and exhaust ducting. Secondly the gas velocity may be too high to actually establish or maintain the flame.

Yes a pilot gas valve assembly will increase the cost of your gas burner system; there is an additional valve (sometimes two), additional pipework, and a more complex controller is usually required to operate the additional valves and flame monitors.

With regards to functionality, as explained above, if you don't use a pilot on larger burners you could have problems in establishing a flame. Or (more likely) you will have issues with unsafe/unstable lighting which would cause an explosion more than a controlled light. There are countless occurrences within the industry of oven/boiler doors being blown off the hinges and exhaust ducting being fired across the room.

The burner will either require a pilot or not and unless you want to modify the burner or operate it outside the manufacturer's instructions then you will probably have a limited choice in the matter.

 

[som1973]

Thank you SEP87 for detailed explanation...