|Better Farming Series 32. Biogas 2: Building a Better Biogas Unit (FAO Better Farming series, 1986, 47 p.)|
|How to build a better small biogas unit|
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.