Building a Substrate Sterilizer (300 - 500 lbs per run)

Main Building Blocks:

• Burner to heat up boiler

• Boiler to produce steam (30 - 50 gallons minimum)

• 300 gallon trough to hold blocks

• Tubing and clamps

• High temperature insulation to wrap around boiler and trough

Other items:

Assembling a DIY sterilizer for mushroom farming is a fairly easy process. The main processes are (1) boiling water in a metal container and (2) sending the steam into a large metal trough for 6 - 8 hours.

1 - Boiling water in a metal container

Some burner which can sustain at least 60,000 BTU will be necessary to heat water in at least a 30 - 50 gallon metal container or boiler. This will then produce steam.

Some kind of hole needs to be drilled into the upper half or lid of the container. This way, the steam, will escape through the hole and into the trough. The lid of the boiler should be clamped on tightly so that there is no heat or steam loss. If possible, a relief valve on the boiler should be built in so that there is no possibility of pressure build up and a small explosion, which would be dangerous.

The boiler should be wrapped in some sort of insulating material such as high temperature fiber glass so as to minimize the heat loss during the process.

The following modifications will also need to be made to the boiler:

• Drill a hole through the top to attach tubing for steam escape

• Attachment of tubing to the top of the steamer

• Drill a hole for the pressure release system

• Drill a hole to install a floating valve to replenish water as needed

• Clamp down the lid securely so no steam is lost through the top unnecessarily

Regarding drilling, per Grok, I will need to get some sort of 2" bi-metal hole saw and cutting oil. Can probably get these at home depot and then make the hole on the lid fairly easily.

Then I can get some sort of 2" OD stainless steel pipe and attach it to the trough using stainless steel NPT pipe nipples, clamps, and high-temp silicone sealant - again per Grok.

Installing a pressure relief valve is definitely extra work, but it is better to be safe than sorry. I will need to get some sort of pressure relief valve - set to 5 PSI should be fine since I'm operating at atmospheric pressure. Then I can install it using a pipe nipple, teflon tape and high-temp silicone sealant. I will need to do a little more research here to ensure that I install this correctly.

Installing some sort of floating valve and then clamps for the lid will also be necessary.

2 - Sending steam into Trough

This part should actually be easier - I just need a hole on the side to let the steam come through. I would also need some sort of metal rack on the bottom so that the steam can wrap around the blocks from the bottom side.

The steam will need to escape from a small area on the top so that pressure does not build up, so that will need to be built in, but that's about it!