Contact Parr Technical Service for help with mass flow meters or controllers. Because these meters must be individually specified and calibrated to the specified gas as well as the desired flow rate and operating pressure, no attempt has been made here to identify the possible selections and specifications. The consideration in selecting mass flow meters is to specify a pressure and a measurement range appropriate to the reaction. Some additional considerations are:

  • Mass flow meters tend to have an accuracy of 1% of the full-scale flow rate. Since the meter must be sized to record the maximum expected flow rate, the accuracy is poor when the reaction is nearly completed and the flow rate is lower. Some systems overcome this by placing two meters in parallel and shifting over to the lower flow rate meter once the initial surge is over.
  • Meters are calibrated for a specific gas. If the user will work with only one gas, e.g. hydrogen, this is not a significant restriction.
  • Electronic flow meters are relatively fragile and must be protected with filters to ensure reliable service.
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