Recycling Fire extinguisher pressure gauges

Has anyone tried recycling the nice 20mm diameter fire extinguisher pressure gauges for use on Models? I have some that are about 20mm diameter with a face marked in red green then red sectors.

It seems that a new face could be added once the gauge had been calibrated.

Chris Gunn

Trust you have a calibration quality test gauge OR lots of weights and attendant fittings.

Regards Ian.

I made one, it was necessary to replace the diaphragm that is in there with a lighter gauge one because the range was too high for model loco use. However I ended up buying one for the loco because I didn't know what the boiler inspectors would say. There is nothing in the boiler code however that says you can't make your own pressure gauge.

Are gauges not just indicators and have nothing to do with boiler safety at least on models. No idea what the boiler test procedure is but I would have thought it would involve setting the safety valves to some external full size calibrated guage.

regards Martin

Ian, I do hold the club boiler testing gear, including a calibrated gauge,.

John, I did not realise the gauge on the extinguisher was was a much higher range, I should have realised the contents will be at a higher pressure then say 100PSI to be effective. I guess that is why they use coloured sectors rather than indicate the true pressure. Also the construction of the body would point to a higher pressure than is useful to us.

Martin the boiler test includes checking the pressure gauge against the calibrated test gauge.

Chris Gunn

These gauges are NOT suitable as they are not direct pressure gauges.They are contents gauges.

If you look closely at one with the pionter axis in the center of the dial you will see the pointer is attached to a coil of flat material. This is a bi-metallic temperature compensator. Thus the gauge indication stays the same as the pressure in the extinguisher rises and falls with changes in ambient temperature. This is obviously not a good thing for a boiler!

Robert G8RPI.

Have a picture of the workings Chris? Gauge out of F/E body.

Regards Ian.

Robert thanks for that, and Ian, I have not taken one apart yet.

I sought advice from the forum before I did anything, and as usual the members came up trumps, and saved me wasting time on this. I have 6 old extinguishers, still viable if the gauges are to be believed, and saw how to turn them into table lamps on Find it, Fix it Flog it the other day, and this led me to think about re-purposing the gauges as well.

Thanks to all