The preferred gas for pressure chamber use is welding grade nitrogen (N2) which is an inert gas and does not react with the plant sample. This has been the standard since the early 1960s. If you do not already have nitrogen, a large “Supply Tank” can normally be bought or rented from a welding or gas supply store at minimal cost.
IMPORTANT – if you have a Model 610 (with an internal tank) – click here to use different instructions. This process is slightly different.
Filling the Portable Tank is easy but care must be taken while trans-filling high pressure nitrogen. You need the following 4 items in order to make a successful fill of the Portable Tank.
- Portable Tank
- Supply Tank (Large filling tank)
- 6 Foot Filling Hose
- Supply Tank Adaptor
Supply Tank (left) – Portable Tank (right)
6 Foot Filling Hose – Supply Tank Adaptor (center)
Next, you will need to connect the two tanks together using the Supply Tank Adaptor and the 6-Foot Filling Hose.
Connect the CGA-580 fitting (screw end) of the 6-Foot Filling Hose into the Portable Tank
Tighten Hand Nut.
Screw the Supply Tank Adaptor into the Supply Tank.
Connect Supply Tank Adaptor and 6-Foot Filling Hose
You will need to pull back on the coupler on the Supply Tank Adaptor
to get a proper connection
Pull gently on hose to ensure properly connected
The tanks should now look like this.
Ensure that the following valves are all shut before proceeding
Supply Tank Valve, Portable Tank Valve and the Pressure Relief Valve
Now you are ready to start filling
Start by opening up the Supply Tank Valve completely
This will allow gas to flow to the Portable Tank and pressure will register on the gauge
BARELY OPEN THE VALVE
JUST CRACK IT OPEN
Allow the nitrogen to slowly fill the Portable Tank
You will hear the nitrogen as it fills the tank. You should take about 1-2 minutes to fill the tank. As the pressure equalizes, continue to open up the valve a little bit more. Continue this process until the pressure has equalized completely. If you open the valve up to quickly and let too much gas into the tank – the valve will become HEATED and could have problems or fail. This is due to the gas compressing into the empty tank.
When the pressure has equalized, seal the Portable Tank first, then seal the Supply Tank. The Pressure Relief Valve will allow you to let the pressure escape from the hose. Now you can disconnect your hose from the Supply Tank Adaptor and connect it to your Pressure Chamber. You are now ready to take measurements.