MKS 937B - 7.4 Capacitance Manometer Installation

MKS 937B Operation Manual
67
Table 7-3 Pin out for 317/345 cables.
7.4 Capacitance Manometers - MKS Baratron
The Series 937B Controller supports a number of capacitance manometers, including the MKS
unheated Baratrons
®
(622A, 623A, 626A, 722A ), and MKS 45 C heated Baratrons
®
(624B,D24B,
627B,D27B). Capacitance manometers measure pressure directly by measuring the deflection of a
thin Inconel
®
diaphragm. Baratrons are widely used owing to their accuracy and reliability. They are
available in full scale ranges from 0.02 to 20,000 Torr, each with a 3-decade range.
See an MKS Baratron instruction manual for complete information on using these capacitance
manometers.
Do not connect heated Baratrons with controlled temperatures higher than 45
o
C.
It may damage the Baratron Module.
7.4.1 Installing a Baratron Capacitance Manometer
Capacitance Manometers may be mounted in any position, however, it is recommended that they be
placed a system with the Px port facing down to allow contamination to fall away from the pressure
sensing diaphragm. Any standard vacuum fitting may be used to connect the Baratron to the system
(VCR
®
, compression, KF flange, etc.). The sensor port will easily carry the weight of the transducer.
Due to the failure of many users to follow the proper tightening procedures for
single or double metal ferrule compression vacuum fittings and the resulting damage
to the pressure sensor, MKS does not warrant this product when such fittings are
used.
7.4.2 Connecting a Baratron™ Capacitance Manometer
A capacitance manometer head is connected to the module with a multiconductor shielded cable. The
module has two female, 9-pin "D" connectors. The Pin assignment for the 9-pin D-Sub connector is
shown in Table 7-4.
Pin Description
1,6 Bridge drive +
5,9 Bridge drive -
2 Chassis ground
3 Signal +
4 Signal -
7 Bridge sensor leg
8 Bridge reference leg