2.0 Warnings
!The DryCal MFS is not rated intrinsically safe and is not for use with explosive
gasses or for use in explosive environments.
!Input Pressure should not exceed 150 PSI
!For use with clean laboratory air or other inert, non-corrosive,
non-combustible, non-hazardous gasses only.
3.0 General Description
The MFS is a non-electrical multiple range flow controller.The MFS provides a sta-
ble airflow for checking any type of flow measurement device.Two precision
regulators, followed by eleven precision porous restrictors, provide control over a
broad range of flow rates, from 10–50,000 ccm. Twelve pneumatic toggle valves
make selecting and adjusting flows quick and simple.
Additionally, an external unrestricted variable pressure flow port can provide a
flow rate of up to 300,000 ccm (pressure dependent.)
4.0 Theory of Operation
The MFS provides flow metrologists a simple and cost effective solution to stable
low flow gas delivery. The MFS works by forcing triple regulated compressed gas
through precision porous metal flow restrictors to create stable gas flows for use
in testing unregulated flow measurement devices.
Gas flow is stepped down though two high precision pressure regulators before
passing through a user-selected precision porous metal flow restrictor.
Precision porous metal flow restrictors are reliable, cost-effective replacements for
orifices, capillaries, or micrometering valves. A porous metal flow restrictor is, in
effect, a multiple orifice device with many very small holes, creating a vast number
of random pathways. Typically, a porous metal restrictor has a porous surface area
500 times that of an equivalent orifice.The flow restrictors used in the MFS chan-
nel gas through hundreds of pores instead of just one, reducing gas exit velocity.
Because gas and particulate move slower through the element, porous metal flow
restrictors incur less wear, and last longer.The porous metal restrictors used in the
Bios DryCal MFS system resist such physical change because of the lower veloci-
ties and virtual absence of erosion, resulting in more consistent, reliable flow
restriction.
32
1.0 DryCal MFS Features
Front and Side
Back and Side
First Stage
Regulator Controls
Second Stage
Regulator Controls
First Stage
Regulator Gauge
Second Stage
Regulator Gauge
High Flow
Outlet Fitting
Connect tubing
here for high flows
Low Flow
Outlet Fitting
Connect tubing
here for low flows
Flow Range
Selector Toggles
External Outlet
Fitting
Connect DUT here
if you are using the
MFS as a stable
pressure source
Inlet Fitting
Connect gas
source here
