Monthly Archives: July 2013

205 Litre (45 Gal) Drums of Diesel For Sale

Drum of DieselMaris Pumps is pleased to announce that we now have for sale 205 litre drums of red diesel.

Have an emergency requirement? Need it now? Contact us on 01246 201111.

We pride ourselves our rapid response times – no longer wait for days for your current supplier – we aim to deliver within 2 hours of your initial call!

Diesel can be delivered with your pump hire or at any time during the period of work.

All drums transported in UN approved containers.

Why you probably need a settlement tank with your hire pump

Settlement tanks are increasingly becoming a necessity on many sites where environmental considerations need to be taken. They offer a degree of protection, ensuring that oil, silts and fines are not discharged back in the watercourse.

The Environment Agency’s Pollution Prevention Guidelines PPG6 states that:

Surface waters and groundwater have legal protection. It is an offence to pollute them.

Silt and oil are the most common construction site pollutants to water. Your site doesn’t need to be next to a river to cause a problem; any pollutants getting into drains can end up in a river even if it’s miles away from site, and can be traced back to their source. Drainage systems, including land drains, act as unseen pathways. If your site is near surface waters or drainage connection leading to surface waters, you’ll need to take extra care to manage your site activities to reduce the risk of pollution.

A settlement tank typically has a number of internal baffle plates or wiers which reduce the flow velocity allowing suspended particles to settle out. Since oil floats on water the baffles can be constructed in such a way that the water flows under the plate, leaving the oil trapped behind the first baffle.

The illustration below shows the flow of water through the settlement tank – entering at the top, the water then flow under the first baffle, leaving any oil floating on top and trapped in this first section, then flows over a v-notch in the second baffle before being discharged.

Illustration of settlement tank showing flow of water

Maris Pumps offer a range of settlement tanks for hire.

What is a submersible pump float switch and which type do I need?

When researching which submersible pump to buy, you will inevitably see pumps which are available with numerous types of float switch, here we’ll describe their operation and two of the most common types.

Mac-3 Pendant type Float SwitchA float switch is a mechanism used to detect the level of water around a submersible pump, allowing the pump to operate automatically – when the water reaches a certain pre-set depth the float switch will trigger the pump to switch on and start pumping. When the water level drops below another pre-set level, the pump will then be turned off automatically and stops pumping.

This automatic operation ensures that the pump will never “run-dry”. The electric motor in a submersible pump is normally water cooled – the action of pumping the water through the pump body keeps the electric motor within normal operating temperatures – when there is no water present, the pump could run-dry and overheat, cause damage to the motor.

Operation of a pendant type float switch in a sump

The submersible pumps we stock can be supplied with a float switch for automatic operation, or without a float switch for manual operation.

For most of our pump range, there are two options for the type of float switch: a free-moving float attached to the pump via an electrical cable, or a tube float which is normally mounted on the side of the submersible pump.

Free-Moving Pendant type Float Switch

JS-250 Submerisble Pump with Mac-3 Pendant Float SwitchThe standard option is the free-moving pendant float – these are generally manufactured from tough polypropylene plastic with a micro-switch mechanism inside. When there is sufficient depth of water the air-filled bulb will float upwards, triggering the micro-switch to power up the pump. When the water has been pumped away and the level decreases, the float will drop, switching the pump off again. This type of float switch generally requires the submersible pump to be installed in a tank or sump and needs approximately 300 mm of space around the pump to operate properly. This ensures the float doesn’t get snagged or tangled on the sump or tank walls.

Tube-type Magnetic Float Switch

RS-150 Submersible Pump with Agma Magnetic Tube Float SwitchThe second option is the tube-type, or magnetic float switch. This is close-coupled to the pump body and has a float which slides vertically inside a tube – when the float is at the top of the tube, a micro-switch turns the pump on and when the float drops to the bottom, the pump is switched off. This type of float switch is ideal for installing pumps is space-limited areas, where a standard float switch wouldn’t have room to operate.

Summary

When purchasing a submersible pump keep in mind the intended use: a manual submersible pump will require you to switch it on and off when required. A submersible pump with a tube type float is ideal for automatic operation in small sumps, and the standard bulb, free-moving pendant float switch is suitable for most other applications requiring an automatic operation.