The Smith Meter Model GPST is a heavy-duty, hermetically sealed, photoelectric dual-channel pulse generator driven by the output shaft of a PD meter. Its two outputs are about 90 electrical degrees apart, so a pulse sequence comparator (for example the Smith CDC-41, CDC-45, or AccuLoad / AccuLoad II / AccuTank with the dual pulse security option) can check for the ABAB sequence and detect noise, transmitter faults or cable faults.
Key specifications
Input power: +12 VDC standard, 40 mA max.; other voltages up to 24 VDC optional
Outputs: Open-collector NPN, emitter to common; quadrature 90 electrical degrees (±10%); max. 15 mA per channel at 24 VDC; logic low 0.4 VDC max.
Maximum frequency: 1 kHz
Operating speed: 0-500 rpm at 200 ppr, 0-400 rpm at 300 ppr, 0-300 rpm at 400 ppr, 0-240 rpm at 500 ppr
Temperature: -20 to 70 °C (-4 to 158 °F)
Explosion protection: Flameproof EEx de IIB T6 (equivalent to Class I, Div. 1, Groups C and D), PTB Nr. Ex-89.C.1065 / CENELEC
Weights and measures: PTB approved
Enclosure: Weather-tight to IP54
Transmission distance: 600 m with 0.5 mm², 900 m with 0.75 mm², 1,500 m with 1.5 mm² shielded multi-conductor cable
How to read the model code
Example: GPST-XP-500-12. Read the code left to right; each position selects one option:
GPST (Type): Pulse Security Transmitter
XP (Approval): Explosion-proof CENELEC/PTB
Pulses (Pulses per input-shaft revolution): 500, 400, 300, 200, 160, 125, 100, 80, 50, 40, 25, 20 or 10
Voltage (Supply): 12 = 12 VDC (standard); 5, 10, 15, 20 or 24 VDC
Ordering information
Per the bulletin:
Find the meter gearing (volume per calibrator output revolution) for the meter model in the bulletin's Table 1
Pick the GPST model that gives the pulses per unit volume required from Table 2 (for example GPST-500 gives 500 pulses per gallon on 1:1 gallon gearing or 100 per gallon on 5:1 gallon gearing)
For distances beyond the cable table, give the instrument type and whether it is capacitive coupled, the output frequency at maximum flow and the distance
Bulletin notes: the quoted speeds exceed the stated 1 kHz maximum (for example 500 rpm x 200 ppr is about 1.67 kHz and 240 rpm x 500 ppr is 2 kHz); Table 2 lists a GPST-250 that is not in the model code, while the code lists 160 and 125; the Table 1 gearing columns are misaligned in the bulletin; "tor" for "for" and "Maxium". Confirm model and speed limits with the factory.
Pricing and lead time are quoted per configuration. Send the model number (or the details above) with your meter model and serial number to Flow Measurement Services for a quote. Specifications summarized from Smith Meter bulletin SS01071E Rev 0.0 (3/93); confirm current data with the factory before ordering.
Smith Meter (formerly FMC Technologies / TechnipFMC Measurement Solutions), now manufactured by Guidant. Flow Measurement Services supplies and services Smith Meter equipment.