Ignition Electrodes

I look after a couple of barrel charring machines - used in the cooperage industry. One of the machines recently broke its ignition electrode rod. Its a 3mm diameter rod that sparks to earth to ignite the gas flame. Because its in the gas flame it gets heated to a cherry red about every three minutes. Anyone have any idea what material it will be made from so that I can try and find a replacement?

The non heated end has a thread cut into it to accept the top from a spark plug, does anyone know what thread is used on the top of a spark plug?

Thanks in advance

Martin

Edited By Martin Cargill on 04/09/2023 20:19:44

If I remember correctly the workshop paraffin/diesel heaters use to have electrodes which once lit stayed in the flame. Would they be of any use not knowing the size of yours just a wild guess.

I have made several ignition electrodes from pieces of tungsten TIG welder electrode. From ignitor contacts to spark plug electrodes. Probably have to silver solderor weld a threaded section on.

NGK: M4

Champion: 8-32 UNC

Your local plumber wholesalers will have electrodes for domestic gas central heating boilers, which do exactly what you need, except for the spark plug thread bit.

Only problem might be persuading them to sell one to you, since I bet you are not Gas-safe registered ! But worth a try.

smash up an old spark plug?

Thank you for all of your comments. The snapped section of the electrode is about 150mm long. There is another section (that I have cut and used to make a temporary repair) that is about 600mm long, This part is not heated so I have made a temporary repair using copper wire, but I want to make a permanent repair using the correct material.

I have talked to the manufacturer of the machine but they are not being very helpful as the gas portion of the machine would have been sub contracted when the machine was made.

I am aware that there are safety implications but the gas side is controlled by a safety relay with ionisation detection (another similar electrode) and if it does not detect a flame within a couple of seconds it shuts the whole machine down.

I do have a relative who is a gas engineer so I will talk to him to see if he can enlighten me any further as to possible solutions.

Martin

You are correct about the safety systems on gas burners, but the whole industry has become closed to non Gas safe engineers. Us mere mortals are not allowed to work on gas boilers, full stop. My domestic gas boiler developed an ignition fault, which was due to a faulty electronic control board, but trying to get advice and spares met with "you are not allowed to touch it, not even only the electronics".

I did fix mine, but just so you are aware of potential problems ahead. Having a tame gas engineer in the family might help a lot, but equally, he might insist that he does the work for you. Good luck.

The requirements of The Gas Safety (Installation and Use) Regulations 1998, impose conditions on all installers and fixers of gas equipment, but the requirement to be registered/approved only applies to employers, employees and self employer persons. The requirement for any person to be competent, does not depend on any trade body registration or other moneymaking scam, such as was applied to electrical work.

My natural inclination is to suggest that persons behind counters in shops, who don't understand this fact, be requested to go forth and multiply...

Although being Gas approved is required for Domestic installations this may not be the case for industrial installations. With domestic there are only a few makers of boilers with integrated burner controllers which are submitted for testing and approval and approval may require spares to be available.

I believe there are no rules governing who can instal a domestic boiler. However the installation must be inspected and signed off before it can be fired up. So I believe you can instal a boiler and connect it to your central heating pipework and instal the gas pipe from the boiler to the gas supply but not connect it. I'm not sure if you need to be approved to turn off the gas and remove an existing installation. You may be permitted to turn off the supply, as I would have thought that necessary for safety but disconnection is debatable.

However if you do your own installation, and the instructions on how to do this are clearly stated in the installation manual, you may find it difficult to get a Gas Approved engineer to sign it off or their fee may be high.

Industrial systems are more likely to be built using components and since they can be so varied in their construction that the rules may be different. Provided you follow recommended practice, document what you are doing and any justifications for variance then this may be sufficient to show competence.

I would have thought that there is no safety implication with the ignition electrode as a failure in this component is allowed for in the fail safe burner control strategy. So provided an exact copy is made, bearing in mind that replacement parts for old systems may no longer be available, then this may be acceptable.

Since the charring unit may be installed in "factory" the factory inspector may need to know and also the company insurance.

CS

Inconel may work, but what about the electrodes used in a combi boiler?  These are Worcester Bosch p/n 87181070870. They are about 2 1/2" long and made to sit within the flame. Pity as a set of newish ones went to the scrapman only yesterday when my old boiler was replaced by a ned 4000 series one.

Edited By old mart on 05/09/2023 13:55:04

I don't know the exact rules but I was told that working on any part of a gas boiler was not permitted without Gas Safe qualifications. I hope I am wrong about that. (I did replace the control board on my own boiler, and did some other maintenance - but nothing to do with the gas path - and it now works perfectly. I also discovered an almost completely blocked hot flow supply pipe and certain design and installation errors with the radiator pipework. I corrected these and the system works much better now than it ever has).

I was also given to understand that if you install your own gas pipework and ask for it to be signed off, request might be refused, since for example, they do not know how well your joints were soldered, but they would technically be liable for any faults.

I would be very happy to be told otherwise.

Screwfix (Plumbfix/Electricfix) will not sell me boiler thermocouples. Happily, the plumbers' merchant across the road will do so. I now have a few in stock.

You can buy as many of these electrodes as you want, no restrictions, put the part number into the ebay search box. There are hundreds listed, and second hand ones are cheap. As I mentioned, the scrap man took a perfectly good set away with the old boiler on Monday when my new replacement was installed by the same man who fitted the old one in 2010, I have just found the original paperwork. Fitting such things to a gas boiler is only allowed for people with Gas Safe approval.

The law is quite clear. You must be competent. You don't need to be gas safe registered. If you are acting as an employer or employee, then you need to be gas safe registered. Otherwise, not.

The dumbing down of the country does not need to apply to those who aren't dumb...

Edited By Mark Rand on 06/09/2023 23:08:04