Greenhouse Collection Chamber
This is what we use to sample surface soil for soil moisture. The dowel rod is inserted into the top of the probe and pushes the sample out the bottom. This small tool is much faster and easier than using a regular soil probe.
Our soil gas collection chambers are made following the protocols outlined by GRACEnet. Go to the following website to see those protocols: http://www.ars.usda.gov/research/programs/programs.htm?np_code=204&docid=17271
This is the lid for the gas collection chamber. It has 4 holes drilled in it. One hole is for the swagelock fitting that holds the septum that allows gas to be removed via syringe and needle. One hole is for the copper vent tube in the side and there are two small holes that hold the screws that hold on the handle. After the holes were drilled, we covered the lid with gorilla glue and placed the silver bubble insulation on it. We then used metal duct tape too hold the insulation together and protect it.
We have one lid that has an additional hole drilled into it to hold a thermometer. We take one chamber temperature reading each time we collect gases.
The lid is 24 gauge metal and was bought online from the WEBstaurant Store. The catalog description is “4 in deep full size standard weight economy stainless steel steam table tray”. $12.28/each.
Insulation ($1/lid), metal handle ($2.50/lid), metal duct tape and glue all purchased at any hardware store.
This photo is the chamber anchor that is pushed into the soil and which provides a lip to clamp the lid on to. This is a 22 gauge metal steam table tray that was purchased online from Gator Chef. It is catalog number 57104, “Steam table tray- Full size- 4 in deep- 22 ga”. $18.87 each. We feel that the heavier metal holds up better to being pounded into the ground.
We clamp the lid to the anchor using 1″ metal spring clamps from the local hardware store. $1.98 each, takes 2 for each lid.
This is the fitting that holds the septum where gas is removed. It is Swagelock part number B-400-1-OR. Cost is $6.00 each. Requires a washer on both sides of the lid and a nut on the inside of the lid. Washers come from hardware store.
The septum was purchased from SGE Analytical and was part number 041881 “Auto-Sep T 9.5 mm” Cost was $1.27 each. Don’t buy cheap septums for this or they wear out really quickly. Use GC autosampler septums.
This is a sideways view of the swagelock fitting from the inside of the chamber lid. The swagelock fitting has a weird thread so we had to buy nuts at a Fastenal store instead of a hardware store. Swagelock sells a nut that fits these threads but they are more expensive than Fastenal. The square thing sticking out of the brass swagelock fitting is the manifold for collecting gases from all quadrants of the chamber.
This photo shows the tubing that goes from the manifold to the four quadrants. Also notice the ¼ inch copper vent tube on the side. The tubing is from Cole Parmer and is item number EW-95665-03 “Tubing S-50-HL 3/32 x 5/32 in”. It is $18.25 for 50 feet. We cut two pieces of tubing at 9 inches each and two at 12 inches each.
This is an outside view of the ¼ inch copper vent tube. The copper line was found in the plumbing department of a local hardware store for $6.68/10 feet. We used 10-12 inches/chamber. It is being held in place with a ¾ in nylon bolt with a ¼ inch hole drilled through it. The nylon bolt was purchased from non-ferrousfastener.com for $0.64/each. Product name is (10676) ¾-10 x ¾ Hex Head Nylon. The accompanying nuts cost $0.43/each, name (11280) ¾-10 Hex nuts nylon. Washers are $0.16/each and are (17596) ¾” F/W Nylon. Washers are probably not necessary.
This photo shows the underside of the lid and the gasket that forms a seal between the lid and the anchor. This is 5/16 x ¼ inch EPDM insulation tape and is found in the window and door insulation section of a hardware store. This tape costs $5.67 for 17 feet. Ours has held up well through one season.
This photos shows production of the tubing manifolds. This was the most time consuming and difficult parts of the chamber construction. The manifold in the front of the photo was ordered from smallparts.com for around $4.00. After determining it would fit our needs, we went back to order dozens more and discovered that the price was then $18/each. The original $4 price had probably been a mistake. To make our own, we used 3/8 x ½ in flat steel for $2.25/ft. We cut it into 1.5 inch pieces for each manifold. It broke a lot of tiny little drill bits but steel and brass are easier to join than aluminum, which would have been easier to drill. We did the drilling on a mill, not a drill press.
The brass tubes were found in the hobby section of an Ace Hardware store. The small brass tubes are 3/32 OD and the larger tube on the manifold end that sticks into the underside of the swagelock fitting is 3/16 in OD. The bottom side of the swagelock fitting may have to be drilled out a tiny bit to get the 3/16 in tube to fit into it. The brass tubes are manufactured by S&K Precision metal or S&K Engineering, Chicago. Each cost about $1.10/ft. The tubes were soldered onto the flat iron using a propane torch.