· an oil drum of about 200 litres, to hold the waste
· a piece of pipe about 15 centimetres long and about 2 centimetres in diameter to fit the oil drum, for the gas outlet
· a pipe T- piece, to connect the gas outlet to the inner tube
· a piece of pipe about 10 centimetres long to fit the T- Piece
· a valve to fit the 1 10- centimetre pipe
The drawing on page 14 in this booklet shows you how these pipe fittings are attached to the oil drum.
· at least 12 metres of rubber or plastic tube, about 2 centimetres in diameter, for the gas lines
· one or more inner tubes, to collect the gas
· if you are using more than one inner tube, you will also need one or more small T- pieces to connect the inner tubes.
15. The oil drum should have one hole for putting in the waste and another hole for the gas outlet. Many drums have threaded holes with threaded plugs to close them.
16. Try to find an oil drum with threaded holes in the top. That way it will be easier to build this unit and to make it airtight.
17. Begin by cleaning the drum inside and outside to remove all oil and grease.
18. Take the metal plugs out of the holes and put them carefully aside, so that you can find them later.
19. First clean the inside of the drum. Pour in a bucket or two of warm, soapy water or other cleaner. Then close all of the holes.
Soaper water or cleaner
20. Put the drum on its side. Roll it back and forth so that the soapy water or cleaner can wash the whole inside. Then open the holes and empty out the water.
empty out dirty water
21. Continue to wash the inside of the oil drum with soapy water or cleaner until it is completely clean.
22. You can tell the oil drum is clean when the water you empty out is clean.
23. When you are sure that the inside is clean, pour in three buckets of fresh water and roll the drum back and forth once more. This is to rinse out any soap or cleaner that is still inside. Then empty it out again.
24. Now clean the outside of the drum with a brush and soapy water or cleaner. Rinse it with fresh water.
25. Open the holes in the top and put the drum on stones with the top down. Let it drain and dry.
Clean the outside
26. When the drum is dry inside and out you are ready to begin.
27. Before you build your new biogas unit you should decide where to put it. Items 26 to 34 in Booklet No. 31 will tell you where.
28. However, do not put this unit underground. If the unit is underground you will not be able to shake it to break up the scum (see Items 109 to 1 13 in this booklet).
29. If your oil drum has a hole in its side, close it tightly. You can use a threaded metal plug or weld a piece of metal over the hole.
Close hole in side
30. Now you are ready to put the gas outlet in the top of the drum.
31. If your drum has two holes in the top, use the smallest one for the gas outlet. Save the largest one for putting in the waste.
32. The gas outlet is made from a piece of pipe about 15 centimetres long and about 2 centimetres in diameter. However, it should fit the hole in the drum.
33. If the hole is threaded, use an outlet pipe that is threaded on both ends. Screw it tightly into the hole.
Screw in gas outlet
34. If the hole is not threaded, use an outlet pipe that is threaded on one end. Weld it into the hole with the threaded end up.
35. If there is only one threaded hole in the top of the oil drum, use it to put in the waste.
36. Then you will have to cut a hole about 2 centimetres in diameter for the gas outlet. Weld in a pipe that is threaded on one end, as shown in the drawing at the top of this page.
Hole for gas outlet
37. Now you are ready to attach the pipe T- piece, the 10- centimetre piece of pipe and the valve.
38. The valve you use must be airtight so that it will not leak gas. You must be sure to screw all of these pieces tightly to the gas outlet.
Screw the pieces
If you do not have a valve, you can tie or clamp the gas line to stop the flow of gas (see Item 48 in Booklet No. 31).
39. Now you are ready to test the drum for leaks. To make biogas, the drum must be airtight.
40. To test for leaks, open the valve, take out the metal plug in the waste hole and fill the drum with water.
Test for leaks
41. Be sure to fill it to the top. Then close the valve and put the metal plug back in the waste hole.
42. Use a piece of cloth to dry any water that you have spilled on the outside of the drum.
43. If you see water leaking from anywhere on the drum, mark the place of each leak.
44. Then turn the drum over on its side. When the drum is full of water it is very heavy, so ask someone to help you.
45. Now check for leaks on the top part of the drum and around the gas outlet, T- piece and valve. If there are leaks here, mark them too.
46. Then open the valve, take out the metal plug and empty out the water. Raise the drum on stones with the top down so it can drain dry.
Empty out water
When you put the drum on stones, be very careful not to damage the gas outlet, the pipe T- piece or the valve.
47. Seal the leaks by coating them with tar, mastic or paint. If there are any leaks around the gas outlet, tighten the outlet, T- piece and valve again. Coat the joints with tar, mastic or paint.
Tar or paint
48. When the sealing is dry, fill the drum with water again. Check that all the leaks are sealed. If the drum still leaks, empty out the water and let it dry.
fill drum again
49. Put some tar or paint inside the drum. Then turn the drum around and around to coat the inside of it.
50. Fill the drum with water again. If it still leaks, start all over again. It is very important to seal all leaks carefully.
51. When the drum is well sealed and no longer leaks, let it dry completely. Now you can begin to prepare the gas holder.
52. As you have been told this unit has an inner tube which holds the gas.
53. If you can get a large truck or tractor inner tube, you will need only one.
54. You can also use tubes from automobiles. However, these are smaller so you will need two or even three.
55. Try to get a large tube because it is easier to attach one large tube than two or three small ones.
56. First check each tube that you are going to use for leaks. Each tube must be airtight. To check a tube for leaks fill it with air.
Fill tube with water
57. Then put the tube in water. You can put it in a pond or in a quiet stream.
58. Turn the tube slowly under the water. Look for air bubbles. If you see any bubbles, mark each place on the tube.
Look for air bubbles
59. Let the tube dry. When it is completely dry, repair all of the leaks.
Repair all leaks
60. Fill the tube with air and put it in the water again to make sure that you have repaired all of the leaks well.
Check again for leaks
61. If there are still leaks, start all over again. It is very important to seal all leaks carefully.
62. When all the leaks are sealed let all of the air out. To do this, unscrew the cap of the air inlet and remove the valve.
Let the air out
63. Roll the tube very tightly. If you have a smooth, round pole, you can roll the tube around this.
64. When the tube is tightly rolled and there is no air in it, screw the cap on the air inlet. This is to keep more air from getting inside.
Screw the cap on the air inlet
When you screw the cap on the air inlet, do not put the valve back, and keep the inner tube rolled up until you attach the short gas line (see Item 70 in this booklet).
65. Now you are ready to attach the gas holder.
66. Cut a short piece from one end of the 12- metre gas line. This is to attach the inner tube to the pipe T- piece on the oil drum.
67. This piece should be long enough to connect the T- piece and the inner tube without being tight. If it is too tight, it may pull off.
68. Fold the short gas line at a place near the centre. Tie the fold tightly with cord. The drawing below will show you how.
fold in centre
69. The fold will keep more air from getting into the inner tube when you attach it to the short piece of gas line.
70. Take the air inlet cap off the still- rolled inner tube and attach the short gas line. Be sure to attach it tightly. You may have to tie it with cord and seal it with tar or mastic. Now you can unroll the inner tube (see the drawings on the next page).
Unroll the inner tube
71. It is very important to keep the gas holder from moving or the short gas line may pull off.
72. If you are using a large inner tube, fit it over the oil drum and place it on the ground. The drum will keep the tube from moving.
Fold in centre
73. If you are using an inner tube that is too small to fit over the oil drum, you will have to keep it in place using wooden stakes.
Use wooden stakes
74. Connect the top of the short gas line to the pipe T- piece on the oil drum.
Connect short gas line
75. However, do not untie the fold in the centre of the short gas line (see Item 101 in this booklet) or attach the long gas line to the valve (see Items 89 to 122 in this booklet) until you are told to do so.
76. The drawings below show you how to connect both large and small inner tubes to this kind of biogas unit.
77. Now you are ready to put waste into the oil drum.