Sequoia Scientific


FlowControl-Sub is a microprocessor-controlled fully submersible 3-way valve system for use in flow-through applications on profiling platforms such as for example CTD’s or profiling floats.

During profiling, the system diverts ambient water through a cartridge filter on either the up- or downcast. When the bottom of the profile has been reached, the system switches so that non-filtered water is measured. The profiles of filtered and unfiltered measurements allow for high-accuracy differential measurements of particle properties, for example absorption, in the entire profile.



  • Pinch valve design for full-port flow and easy replacement of fouled tubing
  • Rapid transition of valve state (~1 s)
  • Auxiliary inputs for analog sensors and Hall Effect volumetric flow sensors (paddlewheel or turbine) [under development]
  • Flexible configuration of valve operation for scheduled or profiling operation, as well as start and stop conditions
  • Continuous output and internal logging of valve state and depth


Mechanical and Environmental

  • Dimensions: 15.625″ (39.7 cm) L x 3.95″ (10.0 cm) diameter (max)
  • Weight: 6.6 lb (3.0 kg) in air
  • Depth rating: 500 m
  • Materials: Black-anodized aluminum pressure case, stainless steel shaft and pinching lever arms, Teflon tubing rollers, acetal resin hold down block
  • Tubing: Designed for Norprene A-60-G 0.5″ ID / 0.75″ OD (US Plastic part # 054282)

Electrical and Sampling

  • Input power: 12-24 VDC
  • Current Draw @ 12VDC: 25 mA / 40 mA / 1.2 A / 2.1 A when idling / sampling w/o auxiliary sensors / switching valve / valve motor stalled
  • Serial Output: RS-232, 19200 baud, 8N1.
  • Bulkhead connector: Teledyne Impulse part MCBH-5-MP
  • Sample rate: 1 Hz
  • Valve switch time: 1 s
  • Pressure sensor: 0-750 psi @ 16 bit resolution (~1 cm resolution, 0.2% full scale accuracy)
  • Thermistor: 16-bit resolution

Software & Downloads

  • FlowControl-Sub - datasheet (pdf)
  • Accessories