Oil & Gas Safety Switch Applications

Explosions and failures that occur in the Oil and Mining industry can have catastrophic results. While not every incident rises to the level of the tragic Deepwater Horizon oil spill disaster in the Gulf of Mexico, the nature of drilling operations in such close proximity to highly flammable oil or gas creates an environment ripe for disaster if not managed properly.

CPI waterproof switches and thermal switches are among the few safety limit switches in the world designed to operate reliably in these environments. Both our waterproof limit switches, and our thermal switch products are specifically designed to withstand extremes of heat, dust, moisture, wind, sand, EMI, and vibration, to allow them to be reliable safety controls in a wide variety of Oilfield and mining equipment.

Unwanted Combustion in the offshore drilling environment generally revolves around two major sources:

  1. Gas and Diesel Engines
  2. The flammability of airborne chemicals.

How Safety Limit Switches Control Flammability

The use of Gas and Diesel engines in close proximity to flammable airborne chemicals poses a twofold risk. In one scenario there is potential sparking that can be caused by an improper fuel/air mix, or improper ignition timing of the engine itself. But in another scenario it is simply the surface temperature of the engine that has the potential to “autoignite” the surrounding atmosphere under certain conditions.

Autoignition temperatures for some chemicals:

Diesel:410 °FGasoline500 °F
Ethanol:680 °FHydrogen930 °F
Butane:780 °FMethanol870°F
Toluene990°FXylene:860°F

One of the major contributors to engine overheating is the possibility of uncontrolled overspeed, especially in diesel engines. This can result in speeds of over 2000 rps but not for long! In order to insure that autoignition does not occur, engine surface temperatures must remain below the autoignition temperatures of the flammable airborne chemicals that surround them.

How CPI J4 Series Limit Switches Work To Prevent Engine Overspeed.

In order to detect and prevent overspeed, ASO valve switches are used to detect the position of the valve. If the valve is closed it means the engine is in a runaway condition. The engine must quickly shut itself off to prevent conditions that are suspected to have been the root cause of the Deepwater Horizon explosion of 2010. Typically Engines used on large generators (2 mega watt range) are required to have ASO valves.

CPI’s J4 type switch is perfect for this application because they can handle the high temperatures (configurable for operation up to 400F) that other switches can’t meet. Variations of CPI’s J4 type switch can also be configured to operate in atmospheric pressure up to 50 PSIG, common to these systems.

CPI’s J4 limit switches have an all stainless steel construction suited for the salt fog atmospheres found on offshore drilling platforms where incorporation of an Air Shutoff Valve (and associated switch) is legislated. Furthermore CPI’s J4 Switch is designed to withstand the high vibration environment found on ASO valves used on diesel engines.

About CPI Limit Switches

CPI has been designing and manufacturing extreme duty switches and sensors for over 50 years. Our J4 series of waterproof limit switches have been deployed in some of the toughest environments in the world, where other switches consistently fail.

Our engineering team can design, manufacture, and qualify the switch you need in your application. We are experts in providing form, fit, and function replacements for switches that fail to last in these extreme, mission critical environments.

CALL CPI ENGINEERING TODAY to discuss your oilfield safety requirements. Or visit us at http:/www.cpi-nj.com