There is one described in one of the Kozo Hirioka books sorry cannot remember which book as I no longer have them.

I suppose you could just start with the Budenberg Gauge company depending on how much detail you want.

If it's in the Heisler book I'll scan it for you. Might take me a day or 2 to find the book. Send me your email via PM

I did make kozo’s dead weight tester many years ago when I had access to some very accurate weighing equipment. As drawn it works very well and has been used by many to check pressure gauges on locos, the only modification I have made is to include an oil reservoir, only needs to be a bit of brass with half inch reamed hole and a piston fitted with an o ring, the piston rod is threaded so piston can be wound in and out of cylinder. In use gauge to be tested is fitted, weights applied and piston turned inwards to force oil under piston to float the weights, sorry for long winded blurb , a pic would have been better, must try harder posting them.

A dead weight tester is something I had often thought of making – it seems so simple ? From the figures given, ie a piston of 0.125" dia would give a ratio of weight to pressure of approx 20.4 ? If this is so them yes an accurate weight is needed, if the ratio is dropped then the accuracy of the weight is less critical ? Then a piston of 0.65" dia would give a ration of 3 to 1 ? and a 56Lb weight would generate a pressure of 168 psi ? A good gauge would read to 5% or better ? NO allowance has been made for the weight of the piston or other devices used to hold or carry the weight ! This is the basics ? Noel.

The difficulty of making one with home facilities is that the piston and bore are superfinished with about 0.0003" clearance, the piston usually hard chromed.

My club has a deadweight tester used to calibrate the master gauge used by our boiler testers. I believe that the key components they used – the piston and cylinder – were sold for a diesel injection pump and met the high finish/very close tolerance requirement. I guess that if it can handle diesel fuel without leakage, it can do this job! Working out the weights required is a straightforward job once you know the piston diameter.

I'm on holiday at the moment and without access to any more details but it might be something worth exploring.

It would be an interesting project, I used to carry out deadweight testing when I was an instrument mechanic, from 10 psi to 25000 psi, not using the same tester. And oxygen gauges which needed a barrier between the oil in the tester and the gauge which was run with trichloroethane iii. The lowest pressure gauges had their own special needs, as the weight of any fluid in the borden tube was enough to affect the readings. They were coupled to the deadweight tester with a low pressure air source. At that time we also had quantities of gauges to refurbish which had the "tru-lume" dials and pointers, radium, that is. The radioactive bits were removed in controlled conditions and after cleaning the dials and pointers were replaced with flourescent modern types. These work in the dark cockpits of aircraft with UV backlighting.

Finding myself awake at this ungodly hour … I had a little dig around t’internet and found this **LINK** which looked promising;

https://modeleng.proboards.com/thread/1996/taunton-model-engineers-magazine

Unfortunately, the embedded link in that post is dead … and currently accessible issues of ‘Oily Rag!’ only go back to 2012

It may, however, be worth contacting Taunton Model Engineers

http://www.tauntonme.org.uk/frontpage.html

MichaelG.

Edited By Michael Gilligan on 29/08/2022 04:04:29

Nealeb jogged my memory ! The injector pump used on the Lister LR, SR,ST and HA series engines, Petter AA and AB and many single or multi cylinder small diesels of the past would be ideal as a starting point for making a dead weight tester. The very accurate piston and a bore vital to success you have ! whilst one could use water as the working fluid, there may be corrosion so the use of diesel fuel or a VERY light oil might be better.Take out the delivery non return valve and even use the injector pipe with an adaptor to your gauge. Remember to set the rack full fuel ! Some fairly simple calculations on piston area and weights applied and you have a dead weight tester ! Noel.