VPAC II - Leak Detection

Leak Detection – VPAC™ TECHNOLOGY

MISTRAS has a range of acoustic leak detection systems and also carries out bespoke designs to meet specific client needs. MISTRAS has in excess of thirty years’ experience in acoustic leak detection on a wide variety of applications in many industries..

VPAC™ technology was originally developed by Physical Acoustics together with BP for estimating leakage rates through valves to flare in refineries, offshore platforms, and other process plant with flare systems. Key to VPAC success is the ability to operate in high noise environments, a result of the short-wavelength anti-vibration sensor technology. Subsequently a joint program between Physical Acoustics, Shell and BP, extended VPAC use to large valves in upstream oil and gas operations. Our clients have published many articles and accolades to the enormous savings that result from a properly run VPAC program. MISTRAS provides advice, training, and services both onshore and offshore.


VPAC™II is the latest generation portable system, intrinsically safe, quick and easy to use. With an 87 dB dynamic range, leak rate calculation in the unit in addition to the software, routing function and noise correction, it is the portable system to use for identifying and quantifying valve leakage in oil, gas, and power operations. VPAC-1278 is VPAC technology for permanent installation, intrinsically safe it operates with any 24 volt galvanic barrier. A two wire 4-20ma logarithmic output to the plant DCS or other system maintains the dynamic range and performance equivalent to the portable VPACII.

Benefits of VPAC
  • Cut sellable gas losses drastically
  • Reduce shutdown time
  • Ensure plant integrity and safety
  • Accurately replace the bad valves
  • Improve maintenance reduce costs
VPAC-1278 | Online valve monitoring subsystem for Oil & Gas
1278 VPAC Subsystem

The 1278 Subsystem, configured for valve leak detection, provides an on-line alternative to the portable 5131-VPAC, which is used worldwide for loss control in refineries, gas plants and offshore platforms. The 5131-VPAC saves >$1m per annum per unit in losses. Based on >15 years experience with VPAC technology, the most cost-effective strategy for installing VPAC On-line is to target the Emergency Blow-Down Valves (EBDV), hydrogen valves, and C2/C3 control valves leading to flare that are responsible for the majority of losses. ESDV’s may be monitored automatically when closed. Difficult to reach valves, for example those on top of towers that may never be surveyed, are another ideal use. The system works with any loop-powered 24 volt 4-20 ma system, (power is derived from the current loop), and is supplied with an intrinsically safe VPAC sensor, ready for direct connection to the plant DCS via any galvanic or zener barrier. When valves do not close properly, or leak for other reasons, the operator knows immediately.

  • On-line real time valve leak detection and quantification
  • Essential for verifying correct valve operation in critical safety systems
  • Can save millions of $’s by identifying losses to flare
  • Intrinsically Safe On-line Valve Leak Monitoring Subsystem
  • Direct connection to plant DCS via loop powered 4-20ma (i.e. no separate power)
  • Works with galvanic/zener barrierss
Valve Squeak

Designed for operations and maintenance personnel to perform frequent valve checks, Valve-Squeak™ is an easy-to-use, pocket-sized through-valve loss detection system. The system isolates leaks of any size and in any valve – saving you thousands, if not millions of dollars – by indicating “no leak” with a green light or yellow LED bar graph showing a range of small to very large. Once a leak is detected, a VPAC™II or VPAC™ can be used to quantify. The high value of Valve-Squeak means it’s possible to have many units in a facility to help a single VPAC™II operator maximize time and resources by quickly identifying and targeting leaking valves for further inspection.

  • Drastically cutting gas losses
  • Find losses before they grow
  • Maintaining plant integrity
  • Cutting back on maintenance costs
  • Moving towards zero emissions
  • A key tool for LDAR programs

What our customers say

. . . by using this instrument we can identify with much more certainty the leaking valve, enabling a quick repair and thus reducing the hydrogen leakage which translates into more hydro treating capacity.

Shell Oil

“. . .our hydrotreater was losing $900,000 per year through one valve. The VPAC helped us justify $60,000 of bypass lines to eliminate future problems.”

Mobil Engineer

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