screw type hydraulic pump pricelist

Highly wear-resistant silicon carbide housings and specially hardened spindlesExcellent efficiencies6 sizes for optimum operating point selectionAvailable fully assembled with mounting plate, valve and pipingAvailable with adapted frequency converter for optimum adaptation to the operating pointEnergy efficient solution in combination with the Brinkmann Pumps Offset regulation while at the same time minimizing pressure peaks during tool changes

For applications involving the transfer of fuels, oils and other lubricating fluids, screw pumps and gear pumps are usually the pumping technology selected. Unlike water based liquids, changes in the temperature often result in a change in the viscosity of these types of fluids. As fluctuations in the thickness of a fluid affects the performance of a centrifugal pump much more than a positive displacement pump, screw pumps and gear pumps are generally the most efficient solutions for oils and fuels.

Screw pumps have a better suction capability and therefore work much better in a long pipeline, for more viscous oils and when air is present in the fluid.A gear pump"s suction capacity is usually less than an equivalent screw pump, making it less efficient under difficult suction.

The screw elements inside the pump have a smaller diameter than gears (for the same capacity), producing less turbulence in the fluid for smoother pumping.Gears need a large diameter for the requested capacity and therefore produce more pulsations in the fluid discharge.

Screw pumps are able to work at a higher motor speed (3000-3500 RPM).Due to the larger gears, rotation speed is limited. If you increase the RPM, the pump loses suction.

The screw pump design has better mechanical efficiency as it uses less power for the same capacity relative to a gear pump, thus saving energy costs.The motor in gear pumps use higher power for the same capacity as a screw pump, resulting in increased energy costs and a larger motor required.

The operation of a screw pump is much softer with less pulsations, less noise and fewer vibrations, meaning longer lifespan.Gear pumps are noisier, more turbulent and cause more vibrations for the pump and pipework to withstand causing a lower working life.

Screw pumps typically have a smaller footprint, making them better when space is an issue.As they generally have a larger footprint, they aren"t as good for installations where room is limited.

Internal components such as the screws generally need to be replaced at the same time to ensure efficient operation, making them quite expensive to maintain.Internal components are often cheaper than those in a screw pump, however as bushes and bearings are in the pumped liquid they are more subject to wear.

Sometimes customers insist on gear pumps, often because that"s what they know, but for the reasons highlighted above we tend to specify screw pumps wherever possible for fuel and oil applications. Popular applications include:Handling diesel and fuel oil

As complexity has grown in processes and new conditions have been added, screw pump technology has attracted increased interest from facility designers, process engineers and operators across the industry. The need to improve energy efficiency and operating flexibility while driving down operating costs is the main drive. It is time to revisit conventional approaches to pump selection and take a look at the evolution of screw pumps, determine how they could improve economics and safeguard the vitality of critical processes in process plants and transfer systems.

This article focuses on pump types with multiple screws. All screw pumps are part of the positive displacement family and as such, are designed to displace flow in direct proportion to the rotary speed of the pump. This runs contrary to hydrodynamic pumps, which rely on kinetic energy.

The tight cavities are formed when the profiles of the screws mesh as the pump rotates, thereby transporting fluids from suction to discharge as it builds up pressure to overcome the downstream back pressure from the system. The screws of the pump are the main pumping elements, where the driven screw or power rotor transfer the torque to one or several idler screws mechanically and hydraulically. The smooth opening and closing pump cavities result in a pump flow with very low pulsations and airborne noise.

Most screw pumps are designed to eliminate axial hydraulic thrust either by using balance pistons or by having the screws in an opposed flowing arrangement. The absence of thrust bearings helps to simplify the pump design and eliminate potential wear and maintenance areas.

Most multiple-screw pump designs are self-priming and can work with low suction pressure. They are also gas tolerant and able to handle free and entrained gases without vapor locking. Low internal fluid velocity and the gentle meshing of the rotors also contribute to very low shear rates, which is especially important for shear-sensitive, non-Newtonian fluids as well as different kinds of emulsions.

The operational flexibility of the multiple-screw pump is manifested by its ability to work over a large viscosity range, from light hydrocarbons to residues and emulsions. The screws are normally case hardened for improved wear resistance, and customized coatings are occasionally used to protect rotor bores, the rotor liner and pump casing.

Today’s family of screw pumps includes designs which were traditionally used in hydrocarbon processing. Applications are now increasingly found in the chemical, petrochemical, food and biofuel industries. Each pump design has its specific set of operational advantages and possibilities. Finding the right type of pump for specific applications is not only important for the process, but also a cost optimization opportunity including the total cost of ownership.

One pump design relies on two screws, one drive and one driven idler screw, which are radially supported by bushings and lubricated by the pumped fluid. The bushings are also part of the axial thrust balance configuration where discharge pressure on one side of the journal and suction pressure on the other side creates a pressure balance, while providing liquid for lubrication and cooling.

The torque transfer from one screw to the other happens by means of a rolling (as opposed to sliding) contact over the screw profile, providing good wear resistance. These screws are running with radial clearance to the bores, which makes this pump design resistant to abrasive wear and suitable for fluids with low lubricity.

Typical applications of this pump design are with fluids like asphalt, bitumen, pitch, emulsions and oily residues as well a variety of process fluids like methylenedianiline (MDA) MDA and mythylene diphenyl diisocyanate (MDI), biofuels and vegetable oils. In order to eliminate vapors escaping from the mechanical seal, it can be replaced by a vapor-tight mag drive to eliminate greenhouse gas (GHG) releases. It is often a good alternative to the timed twin-screw pump. The simplicity and ruggedness without timing gears and only one shaft seal makes this pump type easier to service and operate.

The three-screw pump is used in a number of applications where the fluids range from lube oil in lubrication systems to process fluids like pitch, asphalt and light end products, such as condensate and vacuum gas oil (VGO). The most common pump execution used in process applications has a pumping cartridge, which is separate from the casing, to allow for different installation options. This design uses one driven screw called the power rotor, which is doing the major pump work and is surrounded by two idler rotors. They merely serve as rotating seals for the power rotor and are handling the radial forces supported by long journals formed by the rotor bores. Similar to the other screw pump designs, the thrust load is hydraulically balanced without the use of thrust plates or bearings. The design also allows for higher speed, which results in high volumetric efficiency, even at higher pressure and low viscosity fluids. Typical three-screw pumps can provide flow rates up to 2,000 gallons per minute (gpm) with a maximum discharge pressure of 2,500 pounds per square inch (psi).

Many pump manufacturers use a cartridges design, which works for customized installations. The outer casing can be designed so it matches the envelope of an existing pump and can be a direct replacement without changing pipe connections or the driver. By taking advantage of the flexibility of a cartridge design, important process improvement is possible as shown below. New process conditions are met by having the pump inlet directly bolted to a suction box. The inlet section of the screws is cut open and can act as an auger “pulling” the fluid into the pump.

For light ends, the three-screw pump offers several advantages. The compact and short design, compared to the commonly used horizontal Electrical Submersibal Pump (ESP), makes it significantly smaller and less heavy for the same differential pressure. The internal hydraulic thrust balancing eliminates the need for the thrust bearing arrangement and its lubrication system, which is required for the ESP. In addition, the pump is gas tolerant and can handle liquids that are gas entrained without vapor locking or losing suction. It also runs smoothly and quietly outside and is not affected by any critical speed ranges. It is also not prone to surging or pressure pulsations.

The most versatile of all types of screw pumps is the timed twin-screw pump. Although some manufacturers offer programs with standardized twin-screw pumps, they are often customized for a particular fluid, installation and service. They are designed for larger flow capacities than most other screw pumps and can also be designed for high-discharge pressure. They are used with a large number of different fluids, from nonlubricating, low-viscosity fluids to high viscous heavy oils, bitumen and molasses. Typical twin-screw pumps can cover flow rates up to 6,500 gpm with pressures up to 1,500 psi.

Because the screw profiles rotate without axial and radial contact, the pump is totally independent on the lubricity of the pumped fluid. However, at a lower viscosity the internal clearances increase the internal slip which is a disadvantage for the volumetric efficency. The opposite happens when the viscosity increases, the slip decreases, and the pump becomes more volumetrically efficient. The double suction flow neutralizes the axial hydraulic force, and the rotors are positioned axially in a bearing arrangement, where the radial load is the dominant load.

The twin-screw pump design is widely used in oil fields, refineries, tank terminals, pipelines and chemical plants. As the screws rotate contactless, the flexibility is almost endless when it comes to the nature of fluids it can handle. With variable speed control, a wide flow range can be covered allowing flow and pressure to stay at preset level along with low inlet pressure and entrained gas. Polymer emulsion transfer in chemical plants, blending and charge applications in refineries are good process examples. Another of these is the flare knockout drum pump. The variable pump speed controls the liquid level in the drum, and vapor carry under does not vapor lock the pump as it would with a conventional vertical can pump. The low amount of net positive suction head (NPSH) the pump requires eliminates the pit necessary with a centrifugal pump. The precise flow control is an important aspect in pipeline service where variations in flow can be easily managed by variation of pump speed.

As shown with the types of screw pumps presented, there is almost always a good fit for a particular pumping installation. The widening use of screw pumps is a testament to the versatility and appreciation this type of pump encounters in the marketplace. The development never stops, and recently, new designs for sanitary application have reached the market. The fundamental characteristics of a screw pump lends itself to new fluid handling challenges, and we will continue to see new designs being presented to satisfy new demanding pumping requirements.

Fluid enters the inlet before being transferred to the outlet via cavities between intermeshing screws. Due to the tight clearances slip is extremely limited, and mechanical action is highly efficient.

This is usually another name for a progressing cavity pump where a single screw rotated by a motor rotates within a stator. This is covered in our progressing cavity pump guide.

One screw is driven via the motor, with the other rotated by external timing gears at the opposite end of the unit. Screws can be mounted in pairs meaning up to 4 screws can be in one pump. All screws mesh together ensuring fluid travels along the screws from the inlet towards the outlet.

Triple Screw designs consist of a driving screw and two idler screws. The motor shaft rotates the driving screw which in turns rotates the intermeshing twin idler screws.

The lower the viscosity of fluids being pumped, the higher speeds at which components can be rotated at. Higher viscosity fluids such as Heavy Fuel Oil, molasses, bitumen or other slow flowing viscous liquids must be handled at reduced speeds to enable fluid sufficient time to enter the pumps inlet and ensuring cavitation does not occur. Lowering rotational speed also assists with the NPSH required by pumps.

Screw pumps are known to be efficient, due to clearances within the pump being fine. A gearbox is not always required, meaning mechanical efficiency is one of the highest when compared to other pumps such as gear or vane requiring such accessories.

Due to their design they are self-priming up to 7.5M. Providing screws are lubricated prior to startup, units can be ran dry for a limited amount of time.

Units are typically fitted complete with a relief valve protecting the pump from damage should outlet pipework become blocked, limiting the pumps ability to generate excessive pressure in such cases.

Providing screws are lubricated, units are capable of dry running making them suitable for tank stripping as they can also handle small amounts of entrained gas and air.

Screw pumps NPSH requirement can be as little as 1.5M with designs available for immersion in fluids where viscosity is high or NPSH available is low.

Due to the ability to alter pump speed through a gear box, pumps can handle a wide range of viscosities up to 35,000cst with changes in fluid viscosity usually having little effect on pumped flow rate.

Solid Handling – Models are not suitable for abrasive solid handling which can shorten screw life due to the tight clearances and abrasive affect. Coatings can be applied to reduce wear, but any hard solids >1mm can not be accommodated comfortably. Soft products such as polymerized rubber, mince, molasses, yogurt and Jams can be handled by such units without issue.

Part Replacement – Internal parts can be expensive to replace, with idler and driving screws needed to be replaced as one to ensure parts intermesh without issue and efficiency is maintained.

Marine: Lube oil systems, fuel transfer, sludge transfer, bilge pumping, oily water separator feed, cargo loading & offloading, burner feed for inert gas generator

Our comparison tables below detail how this type of design compares to other pump technologies:Non Pulsating & High efficiencyPulsating flow and less efficient

Can be operated without gearbox. Smaller footprint. Screws are designed to operate up to 3600rpmRequire gearbox. Gear teeth efficiency limited by speed.

Designs can be assembled without rubber parts enabling the pump to be used with solvents and chemicalsPump contains a large stator which is manufactured from rubber meaning the unit can not be used with solvents and certain chemicals

Part cost higher due to part tolerances and tight clearances required for intermeshing. Efficiency lost as screws wearVane replacement is easy. Vanes self-compensate for wear