Oil/Water Separator Overview

Although oil/water separators are presently regulated as waste water treatment tanks, some authorities, include oil/water separators in their underground storage tank regulations. Accordingly, typical design is in conformance with an Underwriters Laboratories approved protected steel construction with robust corrosion control system such as a thorough coating of self-reinforcing, dielectric polyurethane. Additionally, the oil/water separator must be equipped with striker plates and coated internally with polyurethane to protect against internal corrosion. Double-walled oil/water separators provide additional protection with a rugged steel outer wall for secondary containment and electronic detection capability.

Oil/water separator design involves significant engineering. The system should be designed with consideration given to the personnel who must maintain and service the equipment.
– The separation chamber will require provision of three separate storage volumes for:
– oil spill capacity and separated oil storage at the top of the chamber
– sludge accumulation at the bottom of the chamber|
– adequate flow-through detention time for separation of oil from the waste water stream.
– The activities producing a waste water stream at the vehicle maintenance facility will normally be discontinuous; minimum flow rates will frequently be at or near zero. Peak flow rates can be encountered for several hours and will normally be the flow rate of interest for design purposes.
– The oil/water separator must be readily accessible for maintenance and inspection.
– The use of below grade oil/water separators with large access man ways with removable covers are preferred at most locations. The cover should be designed so that it is easily removable by one person without the use of special equipment.
– Inlet piping should be installed with few turns to limit turbulence.
– The oil/water separator should be provided with inlet and outlet valves as a means of shutting off flow for the purposes of cleaning and emergency situations.
– The absence of gravity flow to or from the oil/water separator will make it necessary to pump the waste waters. When gravity flow is not possible, pumping should be restricted to the effluent end of the oil/water separator. Pumping into an oil/water separator will increase the emulsified oil content. When pumping into an oil/water separator, a positive displacement pump (progressive cavity, diaphragm, etc.), at minimum gal. /min, and installed as far upstream as possible, will minimize emulsification.
– The drainage system should be kept from freezing at all times. Install the oil/water separator below the frost line or use a thermostatically controlled steam or electric heater.
– The oil/water separator must be properly vented in accordance with manufacturer’s recommendations and applicable plumbing and safety codes for venting of combustible gases.
– All electrical components and wiring must be in accordance with applicable electrical and fire code standards for location and service intended.

For more information please contact Peter Smyth, Can-Am Instruments Ltd.
1-800-215-4469 Ext 225 psmyth@can-am.net