home made pressure cooker

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lionsman
Stranger

Registered: 08/02/09
Posts: 102
Loc: UK
Last seen: 14 years, 6 months

home made pressure cooker

#10891050 - 08/19/09 04:41 PM (16 years, 11 months ago)

Apologies ELSeta and Jef, this turned into a threadjack on ELSeta's original question. I'll give details of what I did here. There are bound to be other ways of doing it, but keep safety the #1 priority. I guess I need to say that anyone who is not skilled in metalworking should not attempt this. I can't take responsibility for any loss or injury to anyone who attempts this. Obviously a 50 litre vessel at 15 psi is potentially very dangerous if the vessel is not put together safely.
First, legally obtain a stainless steel beer barrel. Student areas are a good place to look for discarded ones (my first find). Publican friends are also useful. Make sure it looks in good condition. In particular the top 'bulge' must be in vgc. as this will form the seal. Here's some pics using a UK barrel, I don't know how they differ wordwide.
First mark a line down through the top bulge (marker pen/paint). Empty barrels still have considerable pressure inside which must be vented. Carefully drill a 3mm hole through the top cut line (pic1), then wait for gas to exhaust.

Using a metal cutting disc/angle grinder, first cut aroung entire barrel along top cut line. Eye goggles and protective clothing are essential! Keep the cut line as straight as possible. The top is then separate with internal syphon tube attached. Cut around barrel again along second cut line (with cutting disc just above bulge centre line).
Cut off the syphon tube flush with spring retainer and clean up until smooth. Discard the thin hoop and syphon. (pic2)

Clean up both cut edges, in particulat the lid edge which must be as flat as possible, as this will form the sealing edge. placing it onto a pane of glass shows any high pints/irregularities. Make the edge round and smooth, finishing with a hand file. (pic3)

To make the brackets, use angle-iron 30mmx3mm cut into 30mm lengths (32). I used a hack saw which is slow, probably better to use a metal cutting disc. Place 2 pieces back to back and weld them together along the edges. Drill 2x9mm holes for fixing to barrel and one 12mm hole for long sealing bolts. Measure aroung the barrel, divide by 8 and make a mark every 1/8 around the top of the barrel base. (pic4)

Hold a bracket against the barrel on one of these marks, with the bracket top against the bottom of the bulge. Mark the barrel through the bracket holes. Drill the barrel on these marks with a high quality 9mm drill bit. The steel is very tough and difficult to get through. I used a hole-punch to make a small dent on each hole-mark before drilling, and at the right drill speed, you can get through no problem.
Bolt the bracket to the barrel, bolt inside and nut outside. smear epoxy resin (araldite rapid in the UK)over the thread and around the hole, so that when it's all tightened up and the glue dry, it's gas-tight. Cut off the excess bolt and file smooth and flush with the nut. (pic5)

Fit all 8 bottom brackets in the same way. Put on the lid, matching up the mark originally made across the cut line. Mark out, drill and fix top brackets directly above each bottom bracket into the 'handle' secton of the lid. Drill 2x8mm holes (or 10mm if using 10mm tubing and fittings) through the lid about six inches apart. Fit out pressure gauge and gas-tight valve to 8mm copper tube (all from plumbing shop). (pic6)

Drill the end out of 4 8mm tube stops. put each tube through one, then through the lid hole, with another on the end of the tube (inside). Use plenty of epoxy resin around the hole and push the 2 stops together, sandwiching the lid between them. Tighten each stop to secure the pipe in the lid hole.
Flatten some 8mm copper tube, bend into an 0 shape, notch each end and fit it to the exposed tube ends, fixing to the inside stop 'gap'. This band of copper over the two inlets stops expanded bags inside the PC from blocking the holes. (pic7)

Glue the ends of a length of P-shaped rubber (see www.sealsdirect.co.uk, under rubber seals (P43)) so that the circle formed fits snugly around the barrel lid, circular part pointing inwards. Put a perforated metal pizza tray upside down in the base, to lift contents above the water layer. Thats everything made! Put in water.
To operate, run a finger along the inside of the top bulge and around the outside of the rubber seal, to make sure there is no dirt/grit. Seat the lid seal into the bottom part, lining up the cross-cut mark on the barrel. Secure top to bottom using 8x10mm bolts/nuts through the top and bottom brackets. Hand tighten them, then sequentially with a spanner until pretty tight (too tight will cut the rubber). PC is now ready to test. The first couple of tests should be done outdoors where there are no people hazards, using a camping stove. Heat until there's a good head of steam, them close the valve. Watch the gauge from a safe distance up to 15psi and a bit more. I have had one up to nearly 30psi by mistake with no problem, but this is not recommended. As there is no safety blow-out in mine I never leave them unattended while using them. This could be fitted if desired.
I guess that's it. I can sterilize 8x 2.5Kg blocks in each.

Extras:

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