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molstic flow metering valve adjustment procedure

This document instructs how to adjust the metering valve to achieve a lower flow at the zero position.

The metering valve is not a shut-off valve. Forcing it closed may cause the needle to damage the seat and will increase the minimum flow. This procedure may be completed with the metering valve mounted to a molstic. It does not need to be removed, but can be if desired.

A higher resolution document is available by the link at the bottom of this article.

Parts Identification
Low and mid/high flow metering valves are sold. Only the internal parts are different.

Fluke Calibration Part Number, Description, Notes
3069786, METERING VALVE, LO FLOW, MOLSTIC-L, Minimum 0, maximum ~8 to 12 slm depending on pressure.

3069799, METERING VALVE, MID/HI FLOW, MOLSTIC-L. Minimum ~2 slm, maximum 100 slm.


  • Remove the handle and the bushing with a 1/8 inch hex wrench.
  • Turn the actuator until fully closed (finger-tight). When new it should already be closed or almost closed. Don’t close with a wrench because the needle can damage the seat. If it won’t turn, loosen the bonnet locking screw with a 1/16 inch hex wrench. Check the flow rate.
  • With the bushing bottomed-out against the top of the bonnet (this prevents the valve from being closed more), tighten the bushing set screw (make sure the bushing set screw is aligned with the flat on the actuator).
  • Align the zero marks on the handle and actuator and tighten the handle. 


  1. If desired to hold a steady flow, tighten the bonnet locking screw in that position.

 End of Procedure


The low flow metering valve (to about 20 slm) is Swagelok PN SS-4BMG-VCR

The mid/hi flow metering valve (to about 100 slm) is Swagelok PN SS-4BMRG-VCR


Contact Fluke Calibration Flow Technical Support at the below link or call us at +1.877.355.3225 if additional assistance is needed.

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