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Level Instrumentation for the Natural Gas Industry

The natural gas industry relies on high-quality, dependable level instrumentation to ensure efficiency and safety. Processes like recovery and storage require innovative level and flow solutions. This blog post discusses level control for natural gas industry applications. This is the second in a series on Magnetrol® offerings for natural gas processing. Be sure to catch up on the first post, from July 14.


Separating the hydrocarbons and fluids from pure natural gas produces pipeline quality dry natural gas. The two principle techniques for removing Natural Gas Liquids (NGLs) are the absorption and the cryogenic expander method. The absorption method is very similar to that of dehydration except that an absorbing oil is used instead of glycol. Once NGLs have been removed from the natural gas stream, they must be separated out, or fractionated.

Challenges: Absorption method level control is typically found on flash drums, separation towers and reflux systems. Cryogenic method level control is applied to the separator and dehydrator.
Level Instrumentation:
Point Level: Echotel® Model 961 Ultrasonic Gap Switch; or Thermatel® Model TD1/TD2 Thermal Dispersion Switch
Continuous Level: Eclipse® Model 706 Guided Wave Radar Transmitter; or E3 Modulevel® Displacer Transmitter
Visual Indication: Atlas™ or Aurora® Magnetic Level Indicators

A Vapor Recovery Unit (VRU) captures valuable volatile organic compounds and other rich gas streams that may otherwise be a significant environmental pollutant. A Vapor Recovery Unit (VRU) collects from storage and loading facilities, reliquefies the vapors, and returns the liquid hydrocarbons back to storage. Methods to recover vapors include absorption, condensation, adsorption and simple cooling.

Challenges: A VRU is a simple, economical process unit that provides EPA compliance and improves operating economies by capturing up to 95% of fugitive emissions. Critical to the VRU is the flash drum where vapors are reliquefied. Liquid level control of the flash drum is essential.
Level Instrumentation:
Point Level: Series 3 External Cage Level Switch; Tuffy® II Float-actuated Switch; ECHOTEL Model 961 Ultrasonic Gap Switch; or THERMATEL TD1/TD2 Thermal Dispersion Switch
Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter; or E3 MODULEVEL Displacer Transmitter

Natural gas, oil, liquid fuel, treatment chemicals, extracted condensate from separators and water are stored in gas fields. Unlike midstream tank farms at terminals and refineries, field storage consists of smaller vessels. Diesel generator fuel, potable water, and fire water are also stored in tanks.
Challenges: Tank level monitoring can be provided with overflow control and alarm systems or shutdown pumps when level falls below the specified low level. Interface controls will sense the beginning of an oil/water interface during tank dewatering and control the water draw-off.

Level Instrumentation:
Point Level: Model A15 Series Level Switch with optional Proofer®; or ECHOTEL Model 961 Ultrasonic Gap Switch
Continuous Level: ECLIPSE Model 706 Transmitter; Pulsar® Model RX5 Radar Transmitter; or Jupiter® Magnetostrictive Transmitter
Visual Indication: ATLAS or AURORA Magnetic Level Indicators

Produced water, wash-down water or collected rainwater require treatment whether they’re re-used for reservoir flooding or simply disposed of. Water collected from process operations contains hydrocarbon concentrations too high for safe discharge. Suspended hydrocarbon droplets in water also hinders well-injection.

Challenges: Treatment equipment is similar to three-phase separators except that water is the main product. Level control is found on skim tanks, precipitators, coalescers, flotation units, and collection tanks and sumps. Interface level measurement is essential for proper draining of clean water and removal of the residual oil.
Level Instrumentation:
Point Level: ECHOTEL Model 940/941 Ultrasonic Gap Switch; THERMATEL Model TD1/TD2 Thermal Dispersion Switch; or Float or Displacer-actuated Switch
Continuous Level: ECLIPSE Model 706 Transmitter; or E3 MODULEVEL Displacer Transmitter
Visual Indication: ATLAS or AURORA Magnetic Level Indicators