Solutions For Valve Oscillation
Contents
1. iS Scheer Frequently Asked Questions FAQ 10 Solutions For Valve Oscillation C50 C100 C101 C140 C180 810 840 Q Why is my mass flow controller oscillating as it delivers the gas A Acontroller that is oscillating or not obtaining its full flow can be the result of one or more of the following Outlet pressure building up or downstream flow restriction causing the outlet pressure to rise above the specification listed on the label Remove unnecessary downstream restrictions and confirm the pressure at the outlet fitting of the controller Compare to the outlet pressure listed on the label Inlet pressure different than specified on label and certificate must be measured close to the controller inlet Sometimes small lines or restrictions reduce the pressure as the gas approaches the inlet fitting while an upstream pressure gauge reads a higher misleading value Confirm inlet pressure and in crease until the proper value within 15 is obtained Regulator problems Sierra recommends double regulation A tank regulator is much to coarse to obtain a smooth flow and consistent pressure Install a second quality regulator Icing or freezing of the gas supply line causing inadequate flow to the controller Inadequate power supply to the controller Verify required voltage and current in literature Flow orientation different than labeled Install controller in the horizontal or vertical orientation as labeled Valve sprin2. g tension out of adjustment This is adjusted as it leaves the factory but the spring and or adjustment can change over time Make a valve spring tension adjustment Consult user s manual or contact Tech Support Liquid or other contamination inside the controller s sensor tube or Laminar Flow Element Inspect and blow out with Air or use a fast drying alcohol and blow out or purge Consult Tech Support if necessary Set point signal not consistent to the controller Pulsing gas supply pressure or vacuum due to a pulsing supply or vacuum pump Sierra Technical Support 1 800 866 0200 j_oswald sierrainstruments com g_russell sierrainstruments com www sierrainstruments co JRO 3 2014 SIERRA INSTRUMENTS NorTH America 5 Harris Court Building L Monterey California 800 866 0200 831 373 0200 www sierrainstruments com
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