Myers-Vacuum Models GT-340A & GT-345B Thermistor Gauges For Sale.
The 340 is an electrically powered gauge for use in harsh environments. The rugged electronics are designed for longevity and occasional accidental misuse. Two analog scales allow the user to take vacuum measurements from atmosphere to 1x10-3 torr. A separate meter scale for the 1 to 100 millitorr range provides increased readability in this critical area. Meter scales are calibrated in dry air pressure units; calibration curves for other gases are supplied.
Measures from atm to 1x10-3 torr
Rugged thermisitor sensor - excellent for high vapor applications
Interchangeable pre-calibrated tubes
High reliability provided through rugged circuitry
Two scales for accurate pressure reading
External circuit control feature available
Leak detect capability on STA.1
Second station can be added on-site
Analog meter indicates direction of pressure change
115/230V, 50/60 Hz operation
More Info on the
GT-340A & GT-345B Thermistor Gauges from Myers-Vacuum
Principle of Operation
A single element is employed in a bridge-type detector driven from a constant regulated voltage source. The inverse resistive characteristics of the sensor unbalances the bridge as pressure changes occur, thereby causing a current change. A microammeter scaled in pressure units measures this current.
Gauge has Leak Detect Mode. Front panel switch allows adjustment of the gauge sensitivity to aid vacuum leak detection.
Connections on the rear panel of the gauge cabinet provide a pressure-responsive output independent of the selector switch. A 10-, 50-, or 100-millivolt high-impedance recorder with suitable attenuating network can be connected here to cover the entire pressure range of the gauge at either sensing station.
The Type GT-340A thermistor gauge and the GT-005A controller are each mounted in quarter-rack modular cabinets. The GT-345B controlling gauge combines these two modules in a single half-rack cabinet. Two GT-340A two-station gauges can be mounted side-by-side for applications requiring four-station operation, with the added advantages of two read-out meters and redundant circuitry.
Automatic Control of External Circuits (GT-345B)
Relay control unit available. This can either be built with the original gauge, or as an accessory (GT-005A). The trip points of the control are independent of the setting of the selector switch. Normally open or normally closed relay contacts rated at 3-amps, 115/230 volts are available for connecting external loads such as safety circuits for tuning off pressure-sensitive components or automatic circuitry for operating vacuum valves at preset pressures. By utilizing the separate adjustment provided, the pull-in and drop-out point of the relay contacts can be set so control is established at any two pressures within the operating range of the gauge. Indication lights on the front panel show position of relay contacts.
Number of stations
1 or 2
Type of Mounting
Bench or panel
Normal Operating Temperature Range
15 to 35ºC
AC Power Input
115/230 volts, 50/60 Hertz
Meter Scale Ranges
0 to 100 milliTorr
0 to atmosphere
0 - 2.5 Volts
EXTERNAL CONTROL CIRCUIT (GT-005A)
Entire range of gauge
Relay Contact Capacity
SPDT, 3 amp, line voltage energized
GT-034 TUBE SPECIFICATIONS
Envelope w/ baffle housing length including base
0.405" diameter sealing surface and 1/8" pipe thread
Thermistor Element Operating Temperature
Maximum Bakeout Temperature of Sensor Envelope
High Vacuum to 60 psig
Ordering information for the components mentioned on this page is listed below.
GAUGE TYPE & NUMBER OF STATIONS
Thermistor gauge, single-station
Thermistor gauge, two-station
Thermistor gauge, single-station w/ relay
Thermistor gauge, two-station w/ relay
Relay control unit
CGB port connector
Fittings for installing sensing tubes in a vacuum system (all have quick-disconnect seal for 3/8" tubulation). To fit 1/2" FPT hole
Bushing for above P/N 061083 CGB Type 3/8" nom. I.D.
10' standard - Station 1
10' standard - Station 2
15' standard - Station 1
15' standard - Station 2
25' standard - Station 1
25' standard - Station 2
50' standard - Station 1
50' standard - Station 2