Seal-Leak Monitoring Mass Flow Meter

Thermal dispersion mass flow monitoring for dry seal centrifugal gas compressors

  • Seal-Leak Monitoring Mass Flow Meter
    Seal-Leak Monitoring Mass Flow Meter

Engineers who monitor natural gas compressors for seal leaks of methane (CH4) for safety, plant efficiency and to meet environmental regulations will find the ST75 Series Thermal Mass Flow Meter from Fluid Components International (FCI) provides precision measurement in small lines for the detection of hazardous, non-compliant and costly gas leaks.

The continuous monitoring of gas compressor equipment for seal leaks is essential for safety, predictive maintenance, operational efficiency and to meet various federal and state environmental regulations. The U.S. Environmental Protection Agency’s (EPA) 40 CFR Part 60, Subparts OOOO and OOOOa, identifies CH4 as a significant greenhouse gas, global warming concern in the oil and gas industry. Production fields, pipelines and storage facilities all rely on centrifugal gas compressor stations that require monitoring of fugitive emissions.

Vent gas monitoring

Natural gas compressor stations commonly utilize dry gas seals that can be a considerable source of fugitive methane emissions. The use of a flow meter to monitor the primary and secondary vent gas on a dry seal serves two purposes. An increase in vent gas can indicate the need for preventative maintenance as the seal quality degrades. Secondly, the meter can be used to quantify the amount of methane leaked into the environment, or sent to the flare, for reporting of greenhouse gas emissions. FCI’s ST75 Series Air/Gas Flow Meter is well suited for small line, low flow measurements in various applications throughout oil and gas industry’s production, processing, transportation and storage industry segments. It measures air or gases from 0.01 to 559 SCFM (0.01 to 950 NCMH) depending on line size and actual process conditions.  The ST75 is factory calibrated and can provide a flow turndown range up to 100:1; surpassing the capabilities of other flow meter technologies

With built-in temperature compensation, the ST75 Flow Meter offers highly repeatable performance in harsh industrial process environments.  It features accuracy to ±2% of reading with ±0.5% repeatability over varying process temperatures and pressures in line sizes from 0.25 to 2 inches (6 to 51 mm).  With an integral Vortab Flow Conditioner, the Models ST75V or ST75AV are ideal for installations with limited straight-run and/or for operating in the Reynolds Number transitional flow range with accuracy of ± 1% reading, ± 0.5% full scale.

For remote mounting

Ideal for the oil and gas industry, the durable and highly reliable ST75 Flow Meter features remote mounting capabilities for hazardous environments where space is at a premium or the measurement point is not easily accessed.  The remote mount transmitter, which has an option for local indication of flow, temperature and totalized flow, can be mounted up to 50 feet (15 meters) away from the flow sensor in the process piping and has two 0.50-inch FNPT or M20 conduit connections for power and output wiring. The ST75 Flow Meter’s scalable dual 4-20mA outputs are standard and user assignable to flow rate and/or temperature and has a 0-1kHz pulse output suitable for remote flow totalization. The instrument can be configured for either 18 to 36 Vdc or 85 to 265 Vac input power, with or without a built-in, two-line indicating display (LCD). The ST75A version also includes either HART or Modbus RS485 (RTU or ASCII) communication protocols. The microprocessor-based design also allows for self-diagnostics and features failsafe output configuration per NAMUR NE43.