Small Boiler Hydraulic Test

How do I go about the small boiler hydraulic test? I made the vertical boiler to understand what is required to make, test and safely operate a steam boiler. This was all as a pre-run to making the Burrell boiler.

The requirement is to hydraulically test the boiler at 2x operational pressure. What is meant by hydraulics is water as the fluid. This is all done for safety as a boiler full of water at pressure will at worst just crack and leak. More likely is I will get a dribble of water from the joints.

garden sprayer

Somewhere, not sure where now, someone mentioned using a garden plant sprayer as a water pump.

Then I saw someone using a small sprayer to refill a miniature steam train boiler whilst being fired.

So I raided the cupboard under the kitchen sink and found this spray bottle. Previously it has been used to spray white vinegar, hence “cleaning only” label.

I removed the plastic nozzle, drilled it out to 4.5mm. I then made up a brass pipe and flange as one part. 4mm OD for the pipe, 8mm OD flange. This then goes into the nozzle from inside and once the nozzle is screwed back in place the flange on the brass pipe seals against the end of the sprayer.

hydraulic pump made from garden plant sprayer

Here you can see the pvc pipe fitted to the nozzle and a cable tie used to secure the pipe. The first time the pipe came off at 100psi and I got wet.

There is a step on both of the pipes. This gives security and the PVC pipe gives me flexibility to make the joint.

hydraulic testing at 50psi

I did the small boiler hydraulic test in steps. The first test was at 50psi. The sprayer works very well and easily gets to this test pressure. I fitted a globe valve to shut off the pressure, but in fact the nozzle was sealed well enough not to need this.

small boiler hydraulic testing

I then went to 2x working pressure. Plus a bit actually.

Again the garden sprayer easily got to above 100psi.

I reckon this sprayer would actually got to somewhere above 200psi without too much effort. I will have to test this sometime.

Leave a comment