MKS Mass-Flo 1159B User Manual (English)

Questions and Answers:

M
Miguel RiggsAug 14, 2025
Why is my MKS Controller oscillating?
- D
  Danielle YuAug 15, 2025
  Oscillation in the MKS Controller can occur due to several reasons: * Too high a controller gain setting: Reduce the gain by turning it counterclockwise. * Incorrect upstream pressure regulator: Check the manufacturer's specifications for the regulator. * Upstream pressure too high: Reduce the upstream pressure. * Amplifier not handling capacitance loads: Install a 150 to 1000 ohm resistor in series with the set point input line.
R
rclarkAug 18, 2025
What to do if MKS Controller does not track set point?
- A
  Austin TaylorAug 18, 2025
  If your MKS Controller isn't tracking the set point, it might be due to improper zero adjustment. To resolve this, zero the meter output as described on page 26.
C
Catherine FisherAug 21, 2025
Why MKS Mass-Flo 1159B indicates approximately twice the known flow and is unstable?
- A
  albert16Aug 21, 2025
  If the MKS Controller indicates approximately twice the known flow and is unstable, it is because the unit is installed backwards in the gas stream. Reinstall the unit in the proper flow direction to fix this.
K
kelly66Aug 25, 2025
Why MKS Controller unit exhibits a large zero temp coefficient?
- D
  Dr. Marissa GonzalezAug 25, 2025
  If the MKS Controller unit exhibits a large zero temperature coefficient, the ambient heater might be out of regulation. Check the placement of the flow meter in the hot system. Return for service.
G
gthompsonAug 28, 2025
What to do if MKS Mass-Flo 1159B does not function?
- C
  Christina ReedAug 28, 2025
  If the MKS Controller does not function, the electronics might be malfunctioning. Disconnect the valve override and return for service.
S
smithstephanieAug 31, 2025
What to do if MKS Mass-Flo 1159B Controller has no output or over-range at zero after warm-up?
- D
  David NelsonAug 31, 2025
  If the MKS Controller shows no output or an over-range at zero after warm-up, the electronics might be malfunctioning. Check the cable type and return for service.
D
Dylan SampsonSep 4, 2025
Why MKS Controller unit produces a large pressure drop or will not pass full flow?
- J
  Joe JenkinsSep 4, 2025
  If the MKS Controller unit produces a large pressure drop or will not pass full flow, it could be due to a clogged sensor tube and/or bypass. Return for service.
C
charles68Sep 7, 2025
Why MKS Controller over-ranges at zero after warm-up?
- L
  lkiddSep 7, 2025
  If the MKS Controller over-ranges at zero after warm-up, it might be because the sensor winding is open. Isolate the MFC and return for service.
M
Michael Miller IIISep 12, 2025
Why MKS Mass-Flo 1159B unit is non-linear or has erratic operation?
- S
  Shannon KingSep 12, 2025
  If the MKS Controller unit is non-linear or has erratic operation, the winding might be out of regulation. Return for service.

MKS Mass-Flo 1159B Specifications

General

Type	Mass Flow Controller
Gas Compatibility	Various gases (specific gases depend on model configuration)
Flow Rate Range	0-5 SCCM to 0-500 SLM (varies by model)
Accuracy	±1% of full scale
Repeatability	±0.25% of full scale
Response Time	<1 second to 90% of setpoint
Control Stability	±0.1% of full scale
Operating Pressure	Up to 150 psig (10.3 barg)
Operating Temperature	0°C to 50°C (32°F to 122°F)
Control Signal	0-5 VDC or 4-20 mA
Output Signal	0-5 VDC or 4-20 mA
Process Connection	1/4" Swagelok® or compatible fittings. Consult specific model datasheet.
Measurement Range	0-5 SCCM to 0-500 SLM (varies by model)