Connecting to pressurized processes using DSC74 sampling cell - DM70

DM70 Quick Guide
Document code
M212551EN
Revision
B
Language
English
Product
DM70
Document type
User guide
  • PTFE tape
  • Adjustable wrench
  • Flat head screwdriver

DSC74 is a Vaisala sampling cell for connecting DM70 to pressurized processes (optional accessory).

DSC74 comes with a quick connector that fits to industry standard compressed air line connectors (suitable for type D, Quick08, NIP08). This allows for easy installation and detachment of the probe without having to shut down the process. Alternative ways to connect are through the 2 different thread adapters (G3/8" to G1/2" and G3/8" to G1/4" ISO) that are supplied with each DSC74 unit.

CAUTION If you use the thread adapters, the process pressure must be shut down for the installation or removal of the probe. If you use the quick connector, the process pressure can be maintained during the installation or removal of the sampling cell. Take a firm hold of the device to keep it in your hands while removing it.

To connect to a pressurized process using DSC74:

  1. Check that the DM70 pressure setting is correct (same as the process pressure). For instructions, see Configuring pressure settings.
  2. Select the quick connector or thread adapter that matches your process fitting.
  3. Carefully seal the threads of the quick connector or thread adapter with PTFE thread seal tape.
  4. Attach the quick connector or thread adapter onto the sampling cell threads. Tighten the fitting with a wrench.
  5. Connect the sampling cell to the process fittings. Seal the fitting with PTFE thread seal tape.
  6. Install the gasket (delivered with the probe) to the nut of probe thread.
  7. Set the probe into the sampling cell. Tighten the probe by turning it from the thread nut. Do not tighten the probe from the handle.
  8. Make sure that the valve of the sampling cell is open. First close the valve, then turn it halfway open again. You can also first open the valve more to ventilate the parts, then readjust it to allow only a small leakage.
    Figure 1. Turning sampling cell valve screw with flat head screwdriver
    To verify that the leak screw is open, close the screw and then listen for a barely audible hiss when reopening the screw (1/2 turn). A light air flow can be felt when placing a hand over the opened valve.
  9. If the sampling cell is installed correctly, there is no leakage in the connections. You can test this by closing the valve temporarily.
    CAUTION Do not open the leak screw more than 1/2 turn to limit the pressure drop in the sampling cell. If the pressure drops too much, measurement accuracy can be affected significantly.