If you’re an energy producer in the United States, you are probably already familiar with the EPA’s Quad O regulations. These regulations were designed to establish emission standards for the control of volatile organic compounds (VOC) and sulfur dioxide (S02) emissions specific to onshore oil and natural gas facilities constructed, modified or reconstructed after August 23, 2011. Quad O states that all storage tanks must have a control device (either an enclosed combustor or a vapor recovery device) by April 15, 2015.

Affected facilities include hydraulically fractured gas well completions, storage vessels, continuous bleed pneumatic controllers, reciprocating and centrifugal compressors, equipment leak detection and repair, and S02 sweetening units.

Crude oil storage tanks hold oil for a period of time to stabilize flow between production wells and pipeline or trucking transportation sites. During storage, part of the crude oil vaporizes or “flashes” and collects in the space between the liquid and the top of the tank. As the temperature of the crude oil increases, the amount of vaporization increases along with the pressure in the tank. As the vapor cools, it condenses and pressure inside the tank decreases.

Vapor Recovery Units are automated systems which automatically start, stop and bypass as pressure is increased in the tanks, and capture up to 95% of vapors to prevent them from escaping and posing health and environmental risks.

Here’s another significant benefit that VRUs provide to producers: recovered vapors consist of light hydrocarbons containing propane, butane and gasoline, which contribute to the gravity of crude oil. When they are vented to the atmosphere a reduction of gravity in the oil occurs, decreasing its value. Because recovered vapors have a much higher BTU content than pipeline quality natural gas, they can result in substantially increased profits for the producer.

To ensure optimal control and monitoring of vapors, a VRU must have reliable instrumentation in place that is capable of accurately measuring low pressure. The NOSHOK 625/626 Series Intrinsically Safe Transmitter is ideal for this application, with low pressure ranges including -4 oz/in2 to 12 oz/in2, 0 oz/in2 to 12 oz/in2, 0 oz/in2 to 16 oz/in2, 0 inH₂O, to 50 inH₂O and 0 inH₂O, to 100 inH₂O (as well as standard ranges from vacuum to 15,000 psi with absolute ranges available).

This transmitter provides the high level of accuracy required for this application, ±0.125% Full Scale (BFSL), and is Factory Mutual & CSA compliant for Class I, II and III Div. 1, Class II and III Div. 2, & Class 1 Zone 0. The NOSHOK 625/626 Transmitter features welded 316 stainless steel construction with no internal o-rings, gaskets or seals, and is entity approved for use with all approved Zener barriers where required.