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capped, or is connected with polyethylene tubing (1/4 inch OD, 1/8 inch ID)to <br /> the surface where it is normally closed off. Polyethylene tubing is generally used <br /> for the vacuum /pressure tube, while either polyethylene or PTFE tubing is used <br /> for the sample collection tube. PTFE tubing is more expensive, but is often <br /> advised when sampling for low concentrations of dissolved organics. <br /> Stainless steel unions (1/4 inch) are used for connecting the tubing to the <br /> lysimeters. <br /> For protection of the tubing and the unions, and to facilitate correct installation at <br /> greater depths, the tubing can be fed through PVC pipe. <br /> The connector on top of the dual chamber lysimeters is 1" NPT, with a standard <br /> pitch of 11.5 threads per inch. <br /> One can use PVC adapters to connect the PVC tubing to the lysimeters. One can <br /> use a 1 by 11/4 white, Sch 40, PVC male adapter. It has NPT threading on one <br /> end, which fits the threading on the lysimeter. The other end is a slip coupling for <br /> 11/4 inch OD PVC pipe. One can also use a 1 inch Sch 40 adapter for 1 inch OD <br /> PVC pipe. <br /> In some instances glue cannot be used. In that case it is best to use threaded PVC <br /> pipe. It comes in 5 ft lengths, and is available from Continental Drilling Supplies <br /> (ph: 650-669-7958). However, in that case one needs an adapter to go from <br /> machine threads on the lysimeter to PVC threads on the pipe. <br /> Installation: <br /> Installation at shallow depths <br /> For shallow depths it is often more convenient to use a handheld auger with a <br /> diameter of 7 or 10 cm,but small motorized drill rigs can also be used. <br /> For shallow depths it may not be necessary to use silica flour for ensuring good <br /> contact of the porous steel of the lysimeter with the soil. Instead one can use dry, <br />