How the Model 1010-P (Pumped Version) Is Typically Used
To make dilutions with the Precision Gas Diluter, connect a sample bag filled with a concentrated (standard) gas to the GAS IN port on the front panel. Connect a second bag filled with a diluent gas, such as air or nitrogen, to the DILUENT port. Frequently, this second bag is not needed, and a "zero filter" can be attached to the DILUENT port instead. The zero filter should contain reagents that absorb or destroy impurities, such as activated charcoal. It should also have a minimal flow resistance; using dust-free granules of sorbent 3 mm (1/8") or larger will generally suffice.
The GAS OUT port may be connected to a calibration hood which allows the instrument to be flooded with the calibration gas. It may be connected directly to some measuring instruments. Often, the diluted gas will be collected in a third sample bag.
Calculate the dilution factor by dividing the desired concentration of the gas by the concentration of the standard gas, and expressing that ratio as a percentage. For example, to make a 50 PPM sample from a 500 PPM standard, use a setting of 10%.
Dial Setting = Desired Concentration / Standard Concentration x 100%
Set this percentage on the front panel dial. When the power is turned on, the flow of gas will begin. The selected concentration will issue from the GAS OUT port within 2-3 seconds.
You can reliably make dilutions of 20-fold (5% on the dial) with very small errors. As the dilutions increase to 50-fold (i.e., down to 2% on the dial), the error will increase somewhat. If you regularly use the Model 1010 for high dilutions, repeat the "endpoint check" described in the manual weekly or more often. Dilutions above 20-fold or 50-fold should be made serially.
The concentration of the output gas can be changed on the fly by resetting the dial. It is not necessary to stop the diluter.
Do not use a Model 1010-P with an instrument that has its own pump. The two pumps will be in contention and the results may be unpredictable.
How the Model 1010-NP (Non-Pumped Version) Is Different
Without a pump built in, the NP version is essentially a passive device. Use it when the instrument to be calibrated has its own internal pump, and can draw its sample directly from the Model 1010 GAS OUT port. The average concentration of the diluted gas is independent of flow rate. At flow rates above 600 cc/min, the concentration will rise and fall somewhat, in time with the regular, once-a-second switching of the metering valve. (If necessary, this pulsing may be smoothed out by adding an additional mixing chamber between the Model 1010-NP and the instrument to be calibrated.)
Turning the Model 1010-NP power switch off does not stop the flow, as there is no pump to stop. Rather, the mixing ratio goes to zero and only diluent gas reaches the output port. This is useful for intermittent baseline setting during calibration.