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Product code: Varisco ST-R Series Centrifugal Self Priming Trash Pump

Varisco ST-R Series Centrifugal Self Priming Trash Pump

Pump Type - Self Priming Centrifugal

Max Flow Rate M³H - 540 M³H

Max Head - 28M

Pump Materials - Cast Iron

Max Temp - 90°C

Max Viscosity - 200 cst

Max Solid Passage - 75mm

Self Priming - Y

Inlet/Outlet Sizes - 50mm to 204mm

Drive - AC Electric, Engine, Bareshaft

Max Suction Lift - 7.5M

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DESCRIPTION

Varisco ST-R Series Centrifugal Self Priming Trash Pump

Flow Rate	Up to 540m³/hr
Head (Pressure)	Up to 28m
Inlet/Outlet Sizes	2” to 8”
Drive Options	Electric Motor, Engine, Hydraulic Motor

The Varisco ST-R series of centrifugal self priming trash pump is designed for transferring fluids that contain large solids in suspension. The largest model in the ST-R series can produce flow rates up to 540m³/hr and heads up to 28m.

The Varisco ST-R series has many benefits, including the following:

Capable of rapidly self priming up to 7.5m without the use of a foot valve.

A two vane semi open impeller is installed that allows the passage of solids in suspension up to 76mm.

Front and rear wear plates to protect the faces of the impeller vanes from wear due to abrasive particles. This increases the lifespan of the pump and lowers maintenance costs significantly.

The pump is installed in a dry area above the fluid, only the suction pipe needs to be immersed in the fluid. This makes maintenance incredibly simple compared to submersible pumps.

Various drive options are available, including; bareshaft, electric motor, diesel engine, engine mounted on mobile trailer and others on request.

The front wear plate can be adjusted from the outside of the pump to compensate for wear if required.

If the pump becomes clogged by rags or stringy solids, the front cover can easily be removed, this provides full access for inspection and maintenance without removing the pump from the pipework.

The internal check valve is easily replaced by removing the impeller inspection cover, the pump does not need to be removed from the pipework.

Robust cast iron pump casing with pressure relief valve mounted on the front cover to vent the casing before opening the cover.

Separate oil filling plugs for the bearings and mechanical seal, complete with sight gauges.

The mechanical seal is self-aligning and oil lubricated. Constructed with Tungsten carbide faces and viton elastomers.

Common application for this centrifugal self priming trash pump include; sewage lift stations, sewage treatment, industrial waste water treatment, pumping any liquids containing high concentrations of solids in suspension and sewer bypass.

Product summary

• Self-priming up to 7.5m without the use of a foot valve

• Two vane Semi open impeller, allowing solids passage up to 76mm

• Front and rear wear plates make the pump highly resistant to abrasive solids

• Removable front cover, pump can be maintained without removing it from the pipework

• Easily removable internal check valve

• Available bareshaft, with electric motor and diesel engine

• Installed outside the fluid

• Front wear plate is easily adjusted to compensate for wear if required

• Oil lubricated self-aligning hard faced mechanical seal

• Independent pump and motor shafts

• Available on mobile trailer if required

• Single phase and three phase 50hz / 60hz motors.

FAQS

Can this pump run dry?

Due to the casing design, a certain amount of fluid always remains in the pump casing when the pump is not operating. This means the pump can run dry without fluid for a small amount of time. It is always recommended to avoid dry running with centrifugal pumps if possible. Centrifugal pumps will incur damage even after short periods of dry running. The mechanical seal requires lubrication and cooling while the pump is operating. Without the presence of fluid, the mechanical seal will overheat and crack, and this may cause the pump to leak and fluid to enter the motor. There is also the possibility that the motor will burn out. Our advice is to ensure that the pump always has access to fluid while running, the vessel or sump on the inlet side of the pump must never run out of fluid while the pump is active. Level sensors or a float switch can be installed in the fluid chamber ensuring that the pump is turned off in the event there is no fluid. Another way of protecting the pump is to fit a dry running device, this will turn the pump off if it detects that no fluid is entering the pump.

What does the term self-priming mean?

A pump must be primed in order to operate correctly, this means that the pump casing and inlet pipe must be filled with fluid and the air removed before operation. This needs to be done manually by the pump operator for a non-self-priming pump each time the pump is used to avoid damage from dry running. A self-priming pump removes these issues by completing the priming process automatically. The air is removed from the inlet pipework and pump casing when the pump is activated. Self-priming pumps are particularly useful for installations with a suction lift on the inlet side of the pump, the pump will draw the fluid up the pipework by creating a vacuum and removing any air that is present. In ideal conditions, a self-priming pump can lift fluids up to around 8m on the inlet side, however this figure is affected by fluid viscosity, pipework bore and other installation conditions, therefore this figure can be much lower from case to case. Allowances must also be made for wear and tear; suction lift capabilities will be much lower for older and worn pumps.

Can this pump be used instead of a submersible pump?

Yes, this pump can be installed in a dry area above the sump if the suction lift height does not exceed 8m. A surface mounted pump has many benefits over a submersible pump, one main benefit being that it is easier the access and maintain the pump.

What size solids can this pump handle?

Please be aware that the figures displayed relate to the largest pump from this range of products, not specific models. For details on solids passage for specific models, please refer to datasheets or contact a member of our sales team.

How do I know what size pump and motor speed is correct for my application?

A clear picture of the pump system is required to make an accurate selection. The main pieces of information required include; a description of the application, bore of pipework, the fluid, flow rate and pressure/head. With these pieces of information, a pump can be sized correctly to ensure it delivers the required flow rate and pressure and that is also operates at its best efficiency point to lower lifetime costs. Knowing if the pump is running intermittently or continuously also allows the correct motor speed to be selected. For instance, a pump running continuously 24/7 will require a 4 pole motor rather than a 2 pole motor. Running the motor slower and oversizing the pump will reduce wear of the motor and the pump, therefore lowering maintenance costs during their lifetime.

How do I know what pump materials are correct for my application?

Firstly, always check the compatibility of the materials available against the fluid being pumped. The main materials to check are the pump casing, impeller, o-ring and mechanical seal. It may be that more than one material is suitable for your fluid and selection could be based on the application type. For instance; cast iron, bronze and stainless steel are all suitable for fresh water. If it is a simple transfer application, then the most cost-effective material cast iron will be best. However, if it is a sanitary application, then stainless steel or bronze are better choices.

What is NPSH and why is it so important?

NPSH is an acronym for Net Positive Suction Head. NPSH measures the absolute pressure present in a fluid.

There are two main ways that NPSH is expressed in a pump system

NPSHa - This is the amount of Net Positive Suction Head available at the pump inlet. NPSHa demonstrates the amount of pressure acting on a fluid as it enters the pump. This measures the amount of pressure between the liquid staying in its current state and forming vapour bubbles (beginning to boil).

NPSHr - This is the amount of Net Positive Suction Head that the pump requires to operate without experiencing the damaging effect of cavitation, thus causing a dramatic reduction in pump performance.

It is very important to pay attention to these values when making a pump selection. Selecting a pump that requires more NPSH than is available in your system will cause fast and long-lasting damage to the pump and thus you will incur large repair costs and downtime.

What does the term best efficiency point (BEP) mean and why is it so important?

The best efficiency point or BEP is a point along the pump performance curve that indicates where efficiency for the pump peaks. When selecting a pump, you must try and get as close to the BEP as possible to ensure that the pump is at maximum efficiency when operating. The closer to the BEP the pump is when operating, the lower the energy costs will be, thus saving significant amounts of money during the pump’s lifetime. Also, vibrations will be at their lowest meaning maintenance costs are lower and the lifespan of the pump is maximised. It is very important to pay attention to the BEP when your pump is selected, as an oversized or undersized pump could cost you significant amounts of money.