MICON 500C Electronic Sequencing
32
234AY00.INS R06
Computer Installation Guide
8.0
PFS 3000 / 3600 PRESSURE-TEMPERATURE COMPENSATION SYSTEM
8.1
GENERAL DESCRIPTION
The PFS 3000 / 3600 system is an electronic ambient temperature compensation system for CNG
(compressed natural gas). It corrects final fill pressures for ambient temperature according to a series
of algorithms based on the ideal gas law:
This system is based primarily in software, but employs a series of analog and digital inputs to interface
the transducer inputs to the system. The control output is the same control valve as the main shut-off
solenoid valve, with some additional annunciation outputs.
The PFS 3000 system, as incorporated into the MICON 500C head, meets both North American and
European design requirements. Alarms are a key function of this system, including alarms generated
externally which the MICON 500C must respond to, and internal faults which must be appropriately
handled by the MICON 500C, according to codes and regulations.
The total inputs consist of 4 analog and 5 digital and/or triggering inputs. Analog inputs include 2
pressure transducers, 1 temperature thermistor, and 1 temperature output from the mass flow meter.
The digital inputs are simple logic level switch inputs. Various degrees of protection are available and
are identified in the hardware description in Table 10, next page.
SPECIFIC WEIGHT OF GAS = ABSOLUTE PRESSURE OF GAS
(GAS CONSTANT FOR GAS TYPE) (ABSOLUTE TEMPERATURE OF GAS)
γ
= p
RT
