Hi,

Some of you might remember a while ago I queried about flushing the insides one of my landrover box chassis with underseal needing something a bit more substantial than the normal rather sad hand pump thing normally sold in Halfords etc.

Well I thought I’d post my sprayer knocked together from an old 19kg propane tank, some hose and a few pipe fittings, total cost was less than £20 thought some of the bits I had already kicking about. I ran it at 60psi but tested it to 110psi with no leaks! The weak point is the hose so test it with water first as if that goes it’s going to empty is entire contents absolutely everywhere which would be just hilarious to see

Some may be worried about welding a propane tank but doing so is very common, you just need to fill it with water right up to the top a couple of times, have a look on YouTube and you see all the great things you can do with one of these. As the tanks are rated to about 500psi an airline is nothing to them. Also I heated my tank right up with a big burner after the water tests to dry the insides out so I wouldn’t pump water into the chassis which would be the last thing I wanted!

As with all pressurised equipment there is some safety things to consider - the main safety ones are - always have the airline disconnected AND the ball valve open when removing the NPT plug from the cylinder for filling, even if it means dumping the remaining contents into a bucket. Then remember to shut the ball valve before reconnecting the air line. Forgetting any of that will either result in a smack in the face from a heavy high speed NPT plug or a huge black mess from hell! Most important is to take your time and THINK what you are about to do before doing it. At all times wear eye protection, preferably goggles so if you get a face full it doesn’t get your eyes.

I used 3 x 5ltr cans of Waxoyl thinned with 5ltr of white spirit mixed up in a couple of big buckets and poured in with a funnel. The hose is a heavy duty garden one, pipe fitting are 15mm and two lengths of 15mm copper pipe. The steel pickup pipe is angled down to the bottom of the tank before welding, hence the angle and there is a fitting welded on to the top of the tank to screw on a quick release valve for the airline. Big plug is a steel ½ inch NPT ( I only did it up hand tight). Because the air is pushing down on to the contents rather than blowing through you don’t need a big air compressor and mine is just a cheapy 2.5hp thing from Aldi.

Any questions or advice just ask. As you can see from the pictures especially if you have used the hand pump versions the flow is quite spectacular!

Cheers.

Classic Mr Whippy that's what you call a ghetto blaster I've also welded fittings on a gas bottle with no issues to use an an extra air reservoir (filled with water like you)

nice approach.. did you use clear or black waxoil?

bought a real wax gun re. not underseal gun running on compressed air works great, not quite you fill the cavity method . parifin gun with wax plus white spirit gun works well all be it with limited reach..

I used the black stuff for the chassis, the clear one is for inside box sections in bodywork and never really sets so is good for sealing seams etc

With this system I wanted to flood the chassis internals to 100% cover all the areas I had been welding, in a couple of years I'll spray it again. I have two holes on the rear cross member with bungs in them to feed the lance in the full length of the chassis. Tbh it's a bit ott for anything else on a car unless really throttled right back or you'll have your whole garage protected! in that case I'd replace the ball valve with a normal screw type.

love it