Pressure gauge location

[Brian GParticipant @briang]

My son and I are currently working on our first boilers, for a pair of SM32 De Wintons to Dave Watkins' "Idris" design. These are less than one bar litre and designed without a pressure gauge, however our intention was to modify the steam turret to accommodate one, as I would rather have a gauge than a whistle, We are also starting on the boiler fittings for a Juliet, which as drawn also has a pressure gauge on the manifold.

I have seen a few comments recently about fitting to a manifold being non- preferred, but wondered if it was still permitted as I am reluctant to tamper with the design of a safety-critical component such as a boiler?

Thanks

Brian

[Brian GParticipant @briang]

On the steam turret/manifold?

[Halton TankParticipant @haltontank]

It is preferable to the pressure gauge directly connected to boiler so the gauge is not affected by steam usage. My Halton Tank loco being an old design has the pressure gauge comming off the steam turret and I had noticed that pressure reading would vary with steam usage, ie, I would turn on an injector and reading would drop 10-20psi, turn the injector off and reading would go back up.

On examing the turret I found it had small steam passages, I have renewed the turret with considerably larger steam passages and now my pressure readings don't vary like they did before.

So I would recommend that if can, connect the pressure gauge directly to the boiler, but if you can't and are going to come off the turret then have a good consideration about the steam passages in the turret.

Regards,

Luigi

[Brian GParticipant @briang]

Thanks Luigi

I had wondered whether the reason was the pressure drop in the restriction, but had no idea it could be that severe.

On the16mm locos the passage from the boiler to the turret has 2.5 times the area of the passage from the turret to the regulator, so i was hoping to get away with mounting the syphon on top, opposite the boiler bushing. We have to take the boiler for inspection before the top plate is fitted, so if necessary there would be a chance (although not a lot of space) to add a further bush if the inspector requires it.

Regards

Brian

[Author]

Posts