Chapter One: General Information
Introduction
17
Chapter One: General Information
Introduction
The Type 1179A Mass-Flo
®
controller and the Type 2179A Mass-Flo controller with a positive
shutoff valve, accurately measure and control the mass flow rates of gases. The Type 179A
Mass-Flo Meter measures the flow rate of gases. Based upon an MKS measurement technique,
patent pending, these instruments use a laminar flow device whose precise indication of mass
flow is achieved through the use of a bypass element in parallel with a sensor tube. The 1179
controller and 179 meter have a three-inch footprint. The 1179 and 2179 controllers feature the
ability to accept TTL level commands to remotely open and close the control valve. The
controller includes a metal cover and RF bypass capacitors, and incorporates a design that
virtually eliminates RFI and EMI interference.
The 1179 Series units can interface to complementary MKS equipment (Type 647, 246, 247,
PR4000) to display the reading and to provide the power, and set point commands.
(Additionally, the 167 unit can be used as a readout and set point generator, but it does not
supply power; the 660 unit can be used as a power supply and readout, though it cannot send a
set point to the flow controller.) Refer to the corresponding manuals for requirements and
instructions.
The 1179 Series flow units are available in a variety of types and configurations to suit specific
needs. The options that must be specified when you order the flow unit include:
•
Connector: 9-pin or 15-pin Type “D” connector, recessed P.C. Edge Card connector,
Digital RS-485, Digital DeviceNet
®
•
Range: 10, 20, 50, 100, 200, 500, 1000, 2000, 5000, 10,000, 20,000, 30,000 sccm
(N
2
equivalent)
•
Fittings: Swagelok
®
4-VCR
®
male compatible, Cajon 4-VCO
®
male compatible, and
¼ inch Swagelok
®
compatible
•
Seals: Viton
®
, Neoprene, Buna-N, Kalrez
®
, all-metal
All 1179 controllers have normally closed valves.
Design Features
The design of the 1179 flow controller incorporates an advanced flow sensor, a new control
valve, and an optimized bypass. (U.S. and Foreign Patents; Patents Pending on the sensor.) The
latest generation two-element sensing circuit provides accurate, repeatable performance even in
low flow ranges (< 10 sccm). Low temperature effect from ambient temperature change and a
low attitude sensitivity effect are also ensured. The newly optimized sensor/bypass arrangement
minimizes the flow splitting error for gases with different densities, which dramatically improves
measurement accuracy when gases other than the calibration gas are used. The surface mount
