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Wherever or whenever it is possible that oils may leak into collected rainwater, Darcy has the solution.

Darcy can now offer a discriminating pumping system that will safely remove collected rainwater whilst preventing any oil that may be present also being removed. 

Purpose 

The Darcy Float Switch Oil Discriminating Pump will discriminate between a conductive and non-conductive liquid, such as oil and water, in order to determine and control what liquid is actually pumped.  The unit and probes have been designed to be used in conjunction witha  standard submersible pump and float switch.

The Environment Agency will accept any discriminating pumping system that does not discharge any oil whatsoever.  To achieve this it is therefore essential that any oil, whether it be in small globules, emulsified or in a concentrated form, never enters or touches the pumps inlet.  

The oil discriminating submersible pump manufactured by Darcy cleverly sits in a level of water in the bund sump that acts as a ‘shield’ protecting the pump inlet that is located at the base of the pump resting on the sump floor. 

Application areas

The unit has been designed for use within any area or sump that normally collects water but potentially could contain some oil such as:

• Bunded areas surrounding Oil Storage Tanks
• Bunded areas surrounding Transformers
• Sumps or trenches in run off areas where oil could be stored or used
• Lift shafts
• Wells

The likelihood of oil being present in a bund is great, especially in the presence of older transformers or tanks that can be prone to leaking creating an ever increasing layer of oil.  All tanks have the potential to rupture and there is a threat of a transformer exploding.  For this reason it is essential that the full capacity of the bund is maintained at all times and rainwater is not allowed to settle.

Equipment

The unit consists of an electronic control, which is connected in line with the pumps electrical supply together with sensors that are attached to the underside of the float switch that discriminate between oil and water.

General Operation

The electronic control unit is fitted in-line with the power supplied to the submersible pump. Two conductivity sensors are supplied and should be attached to the underside of the float switch. These sensors when immersed in a liquid, determine whether that liquid is water (a conductive liquid) or oil (a non-conductive liquid). When water is detected the pump will be allowed to operate normally by float switch control.  However, if oil is detected the pump will be prevented from operating.  In cases where a reasonably substantial amount of oil has been allowed to accumulate in the sump and therefore this oil floats on top of any subsequent rainwater collected, the control is capable of removing the water from beneath the oil layer.

Optional alarms

The control unit has in-built circuitry to produce various alarm conditions if required.  This is achieved by connecting a further separate float switch to the control and positioning it within the sump adjacent to the pump and its float switch so that it activates (moves the roller ball to activate its internal micro-switch) at a slightly higher position than the pumps float switch.  If this float switch ever reaches this level and is activated, then one of the three possible events has occurred:

1. the pump has failed and the water level (conductive liquid level) has risen
2. the ingress of water (conductive liquid) within the sump is greater than the pump can cope with
3. the sump has filled with oil (non-conductive liquid) or there is a layer of oil suspended on top of the water in the sump covering the sensors on the float switch

Positioning the control unit

The control unit should normally be positioned within 5 metres of the pump and securely attached to a suitable surface.  It can however  be positioned further away, but obviously extra cabling will be required.

Important note: If the control unit is to control a submersible pump within a bunded area, then it MUST be positioned OUTSIDE the bunded area.

For further details and to request a quotation or demonstration please complete the form below: