split flow hydraulic pump brands

ONE Dynex pump can supply multiple actuators, and synchronized movement can be achieved without flow dividers. Dynex pioneered this Split-Flow® technology over 60 years ago!

The checkball pump design uses individual piston check valves, offering a unique advantage among hydraulic pumps. Each pumping chamber can be isolated, and the output from each piston can be used separately.

Combination of VE43D/VP43D and overcenter valve OC Over-Center Valve (OC): The overcenter valve (counterbalance) is designed to control the movement of the cylinder subject to a negative load. This valve is suitable for double effect or oil return cylinders only. The overcenter valve permits a controlled lowering phase of the load avoiding danger for the operator and for the hydraulic system itself. The valve is set to factory values, no reguation needed by the operator. The unidirectional flow control valve (RFUA) is a cheaper alternative to the overcenter valve: in this case, the operator must shut the valve before the lifting phase, to gradually open it during the lowering phase to set the return’s speed. This is obviously a cheaper way to obtain speed control during the lowering phase but the operator is exposed to danger due to a less accurate management of the load. Assembled on a split flow pump, the overcenter valve allows a fine control on the lowering phase too.

RHI is proud to represent Dynex and their checkball pump design, with its individual piston check valves. This design offers a unique advantage among hydraulic pump designs. With this design each pumping chamber can be isolated, and the output from each piston can be used separately!

This means ONE Dynex pump can supply multiple functions and synchronized movement without flow dividers. They call this Split-Flow® technology with it"s own patent.

It is common practice for most American Petroleum Institute (API) pump installations to incorporate 100 percent capacity spares. It is also common practice to install two pairs of pumps, taking suction from the same source, for different process services (see Figure 1, PFD 1).

Process designs using two 100 percent capacity pumps, rather than four, are sometimes used. For example, some operations oversize pumps to envelop two different process conditions—typically low flow, high head and high flow, low head (see Figure 1, PFD 2). The larger motors required for this option waste energy compared with four-pump designs. Another option is to use two 100 percent capacity pumps with the split flow feature (see Figure 1, PFD 3).

Split flow pumps separate or split a pump inlet flow stream into two separate outlet flow streams using hybrid hydraulics—for example, different impellers in the same pump casing (see Figure 2). The first stage is selected for the total flow of both outlet streams at the head of the first outlet stream. The second stage is selected for the lower flow at the higher additional head of the second outlet stream.

Split flow pumps conform with API Standard 610 and may be either overhung horizontal (OH2) (see Figure 3) or vertical inline (OH3) with low-flow secondary impellers, or between-bearings horizontal two-stage (BB2) (see Figure 4). Split flow pumps are “two pumps in one” with a common driver (motor or turbine).

The overhung split flow design uses drilled-hole, disk-type secondary impellers. This shortens the shaft cantilever (compared with conventional impellers) and produces flow below 50 gallons per minute (gpm) without the “back-on-the-curve” problems inherent with conventional impellers. This includes the capability of dead-heading the secondary impeller, assuming the primary impeller is operating above its minimum safe flow.

Pump-sizing criteria and common practice limit the use of overhung pump types. The split flow feature of one inlet and two outlets for different head-capacity (H-Q) conditions is available for between-bearings configurations, including tandem as with the overhung design, and for larger sizes, with impellers oriented hub-to-hub or eye-to-eye and with double suction availability for primary impellers (see Figure 4).

Split flow pumps are used for dual-service applications—for example, where liquid from a common source is pumped to two separate dispositions (see Figure 2).

Most API pump services use two 100 percent capacity pumps—one operating and one installed spare (see Figure 1, PFD 1). Alternatively, to reduce the equipment count, some system designs use oversized pumps to envelop both the high-head, low-flow and low-head, high-flow streams (see Figure 1, PFD 2). This results in redundant H-Q capability and requires larger drivers than the four-pump designs.

This design also provides maintenance benefits. When overhung pumps are used, two seals replace four. When between-bearings pumps are used, four seals replace eight.

API Standard 610 illustrates rotor vibration at various flows with respect to the best efficiency point (BEP) (see Figure 5). Pumps are often run “back on the curve,” meaning at flows between the BEP and minimum safe flow. This results in higher rotor vibration and reduces the mean time between repairs (MTBR).

Selecting suitable high-head pumps for flows below 50 and 80 gpm (typical BEP range for 1-inch API pumps at 3,550 revolutions per minute [rpm]) is a challenge. The split flow use of hybrid hydraulics enables approximately half of the less efficient, low-flow head to be produced by the more efficient, higher-flow primary impeller (see Figure 6).

The first pair of split flow pumps began commercial operation in a California refinery in June 1996. The service was fractionator reflux with an HGHT unit.

The pumps also would need to be the more costly between-bearings type because of an impeller diameter exceeding the user’s 13-inch maximum impeller diameter criteria for overhung pumps at 3,550 rpm (see Figure 6).

A 2011 process revamp removed these pumps from service. The operators documented that the pumps satisfied all premised requirements, including reliability, during their 15 years of service.

Deleting hub wear rings and balance holes from the primary impeller (a standard feature with most OH2 designs, including the original split flow prototype) enhances both hydraulic efficiency and net positive suction head (NPSH) margin by precluding bypass into the impeller eye.

SFP-Series, Split-Flow Pumps ▼ SFP 421SW and SFP 404SW (pressure gauges and retract valves are not shown) Multiple Outlets with Equal Oil Flow Typical Split-Flow Pump Applications Split-Flow pumps distribute an equal amount of hydraulic oil to a maximum of 8 outlets. Smart valve technology allows both controlled lifting and lowering of heavy loads. Pressure compensated flow control This unique feature to our Split-Flow Pumps will ensure both smooth lifting and lowering. Independent of load distribution. • 2, 4, 6 or 8 split-flow outlets • Individual or simultaneous valve operation with advance/hold/retract function • Joystick (manual) controlled or pendant (solenoid) controlled valves • Flow per outlet ranging from 0,32 to 4,2 l/min at 700 bar • For double and single-acting cylinders • Pressure compensated flow control • Adjustable pressure relief valve per circuit • All models include pressure gauges • Reservoir: 20, 40 or 150 litres. ▼ During manufacturing of container units, the Enerpac SFP404SW Split-Flow Pump with 4 outlets provide both lifting and load distribution function. The container units weight between 70 and 120 ton and are complete equipped as full operational shelter for specific applications in power-gen, mining and construction industries for on-site use. For lifting applications Split-Flow Pumps are an efficient and safer alternative than using individual pumps. Where synchronization of maximum 4% is acceptable split-flow pumps are a safe and economical solution. Application examples: • • • • Bridge deck lifting for bearing maintenance Stage lifting in construction and shipbuilding Skidding to move structures and buildings Levelling of constructions like wind turbines. Remote Control Pendant Split Flow pumps with solenoid valves include a remote pendant with selector switches for each individual outlet, allowing single or multiple cylinder operation. Lifting Cylinders For a complete line of Enerpac cylinders, see the Cylinder and Lifting Products in

The HSP split flow, hydraulic pump is designed to deliver equal volumes of oil from each individual control valve regardless of any variations in the hydraulic pressure.

Each valve outlet is connected directly to an independent internal piston pump which is driven by a common electric motive force. This allows each internal piston pump to deliver an equal amount of oil flow per minute regardless of any variations in the required operating pressure at each control valve outlet.

With HSP split flow pumps lifting and positioning large, unevenly weighted loads using multiple jacking points in a synchronized, level lift and controlled manner is easily achievable. Individual control of each valve is via a specially made electric control box with easily identifiable on/off switches for each applicable valve plus a synchronized lift control button for all of the selected control valves. There is a remote hand pendant control system which is wired to the pump mounted control box.

Maximum working pressure of all HSP pumps is 700 Bar with an externally adjustable pressure relief valve for easy pressure adjustment between 70 and 700 Bar. Electric motors are 380/440 volt three phase operation.

Enerpac model AM41 seven port split-flow valve enables control 2-4 single-acting cylinders simultaneously. All ports 3/8″-18 NPTF, maximum 10,000 PSI.