The DSC74B and DSC74C sampling cells are enhanced versions of the DSC74. The body is designed in a way that it is possible to measure at both system pressure and atmospheric pressure.
The DSC74B limits the flow rate with a fixed leak screw. The flow is optimized for pressures 3 ... 10 barg. The fixed leak screw eliminates the risk of opening the leak screw fully by accident and this way emptying a gas vessel. The maximum flow can be increased, if needed, by removing the leak screw and adjusting the flow manually with the valve. Harmful gases can be recovered by connecting a collection system at the outlet (not available from Vaisala).
In the basic operation of the DSC74B, the gas flows to the sensor from the front and the outlet is on the side. To have the measurement done at atmospheric pressure, the inlet and outlet are reversed. Then the reducing parts supplied (G3/8" to G1/2" or G3/8" to G1/4") on the outlet side help to protect the sensor from ambient humidity coming in.
DSC74B consists of the following parts:
- Sampling cell, thread 3/8"G
- Connection part with a needle valve and an integrated leak screw
- Reducing Nipple (thread adapter), G3/8" to G1/2"
- Reducing Adapter (thread adapter), G3/8" to G1/4"