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Pressurised Sand Filters

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These filters are the most popular method for removal of turbidity from water.These filters use natural sand as a filtering agent trapping debris as it passes through. The Pressure Sand Filter consists of a multiple layer of sand with a variety in size and specific gravity. These Filters are designed to remove turbidity and suspended particles present in the feed water with minimum pressure drop. These Filters are custom designed to suit the process requirement. These filters are offered in Mild Steel, FRP or SS construction with face piping and associated Valves.

Sand filters work by allowing water to cycle through a vessel that contains sand. The water flows through the sand with ease, but larger particles are unable to pass through. As more debris becomes collected by the filter, the efficiency of the filter will start to increase as well; the debris will actually help to keep smaller particles from passing through the sand.

Materials Filtered by Sand

A range of materials will be captured by your sand filter. Larger materials such as leaves, gravel, and insects won't be able to pass through the sand at all, and even smaller materials will be stopped as the water from your pool moves through the filter canister. Even small particles between 20 and 100 microns in size will be captured by the sand within your sand filter, and particles smaller than that can potentially be contained as the filter collects debris. Particles that pass through the filter initially may be filtered out later as the water in your pool cycles back through the filter.

Construction

The Pressure sand filter consists of a pressure vessel either vertical or horizontal, with a set of frontal pipe work and valves, graded silica quartz sand supported by layers of graded under bed consisting of pebbles and gravels, a top distributor to distribute the incoming water uniformly throughout the cross section of the filter, and an under drain system to uniformly collect the filtered water.

Maintenance Requirements

As material is captured by your sand filter, occasional cleaning and maintenance is required. The more dirt and debris your filter has in it, the more pressure will begin to build within the filter canister. Take note of the initial reading of the pressure gauge on your swimming pool's sand filter, then check it every week or two to see if there has been an increase in pressure. Once the pressure has increased by 8 to 10 pounds you will need to clean the filter by performing what is known as a "backwash cleaning" to remove the excess dirt and other debris from the sand. Backwashing a sand filter is easy. Shut down the pump cycling water through the filter and allow it to stop completely. Once the pump has stopped, unroll or attach the backwash hose and turn the pump's setting valve to "Backwash." Turn the pump on and let it run. The water will start coming out clear, and then will begin to get darker as more dirt and debris comes out. Allow the water to run until it becomes mostly clear again, then shut the pump off. Turn the setting valve to "Rinse" and allow the pump to run in the rinse cycle for 30 to 45 seconds. After you've rinsed the filter, put up the backwash hose again and reset the pump to its normal setting before starting it up again.

Changing the Sand

Unfortunately, even regular backwashing won't keep a sand filter running efficiently forever. Eventually the sand within the filter container is going to need to be changed, though this will generally only have to be done once every 5 to 7 years. Changing the sand isn't difficult, though it can be slightly time-consuming depending on the size of the vessel that the sand filter uses. Start by performing a backwash, leaving the pump turned off once it is finished. Open the pressure valve on the top of the filter vessel to release the pressure from within the sand filter, then open the drain valve on the bottom of the vessel to release the water inside. Begin loosening the bolts holding the vessel together, alternating from one side to the other in order to prevent damaging the container with excessive stress on one side. Remove the top of the canister, then scoop out the sand contained inside of the filter vessel. Once you've removed the sand from the filter, check the lateral components inside to see if they are overly loose or broken. Replace any laterals that have broken or come loose, then fill the container half full of water to help protect them from damage as you start adding sand. Once the filter is full of sand, reattach the top of the canister and perform another backwash before you begin pumping water through the filter again.

Mark Controls - Types of Sand Filters

FRP Pressure Sand Filters up to 2000 mm Diameter

Vertical MS Pressure Sand Filters up to 5000 mm Diameter

Horizontal MS Pressure Sand Filters up to 4000 mm Diameter

Advantage - Mark Controls Sand Filters

Highly effecient in turbidity removal

Available in FRP, MSRL, MSEP & SS

Standard and effective multi grade sand media.

Low Pressure drop across the vessel

Optional Air scouring available.

Manual, Semi Automatic & Automatic Options

Sand Filter - Areas of application

Raw Water Treatment

Waste Water Treatment

Reverse Osmosis

Ultra Filtration

Cooling Water Treatment

Boiler Feed Treatment