Sundyne Pumps Selection Guideline

1. Purpose

This procedure provides guidelines for selecting vertical, high speed, single stage (Sundyne) pumps.

2. General

A Sundyne pump is a vertical, single stage, centrifugal pump, generally driven by a motor and gear set integral with the pump. Sundyne Corp. of , and Nikkiso Co. Ltd. of , manufacture the pumps. The range of pumps available from Sundyne has speeds from 3000 rpm up to 25,000 rpm, depending on the differential head and flow requirements. Inflection Point Engineering specifies Sundyne pumps, as opposed to more conventional pumps, for applications which present a significant cost, control, or reliability penalty if the alternative reciprocating or two stage or multi-stage centrifugal pump were used. Cost-wise, for analysis basis, we consider Sundyne equal to single stage process pumps but considerably less expensive than two or multi-stage pumps. If a single stage process pump can be selected, that is chosen so the purchaser can go out for competitive bidding from multiple vendors.

Sundynes are built to the API 610 Standard (Type OH-6), with a list of Inflection Point Engineering-approved exceptions, so they can be used for flammable services such as hydrocarbon. Currently, Sundyne is the only Inflection Point Engineering-approved high speed, integrally geared pump. Therefore we call it out by name in the 501 Inflection Point Engineering Project Specification. (See Note 40 of the 501 Inflection Point Engineering Project Specification)

The pump selection tool in the Hydraulics program will choose a Sundyne when appropriate. However, the BEDQ, Section 5.6 h, must be checked to see if a specific Owner has agreed to allow Inflection Point Engineering to specify vertical, single stage, high speed pumps.

3. Selection Guidelines

To manually determine if a Sundyne is appropriate reference .

Limitations

Sundyne pumps are limited to the maximum operating conditions shown in the table below:

Note: Sundyne pumps are available at higher design pressures. Consult pump specialist if a pressure higher than 2160 psig is desired.

3.2 Reciprocating Pump Services

Use Sundyne pumps in many traditional reciprocating pump and proportioning (variable stroke) pump services for the smooth flow characteristics, ease of control, and a lower maintenance requirement. For low to medium flow rates up to 25 gpm (5.7 m3/h) and medium to high head duties from 165 ft (50m) to 1500 ft (480m) Sundyne pump efficiencies are only about 25% (less than the 75 to 80 percent range expected for reciprocating pump services). At the commonly low power levels, Sundyne and reciprocating pump capital costs are comparable. Sundyne pumps are advantageous when handling flammable or toxic materials due to the small amount of leakage associated with the rod packing on reciprocating pumps. Also, the only flow control for a reciprocating pump is by spillback or variable speed driver.

Maintenance on a Sundyne is considered less than for a reciprocating pump because there is no packing or valves to replace. Typically, unless the service is intermittent water, a Sundyne is chosen over a reciprocating pump.

3.3 Conventional Centrifugal Pump Services

For heads up to about 660 ft (200 m) on low flow applications under 350 gpm (79.5 m3/hr) a conventional 3550 rpm centrifugal pump may be used. Typically it is not preferable to “sole source” so a conventional centrifugal pump is chosen. However, when the conventional pump minimum flow requirement is greater than the required process flow, a constant spillback to suction is required which may result in excessive energy usage. Sundyne pumps have considerably lower minimum flow requirements which, for many applications, eliminates the need for a continuous spillback.

3.4 Multistage Centrifugal Pump Services

Consider Sundyne pumps for applications where multistage vertical or horizontal centrifugal pumps may be used up to heads of 5500 ft (1676m). Usually, Sundyne pumps are only slightly less efficient, and installation is considerably simpler, especially compared to horizontal multistage pumps. The overriding consideration for choosing a Sundyne pump is substantially lower cost, which is about one-fifth the capital costs for horizontal and vertical multi-stage centrifugal pumps. Also a multi-stage may require a continuous spillback to operate above the minimum continuous flow. This wastes utilities.

3.5 Maintenance

The Sundyne pump is relatively maintenance free compared to a reciprocating pump with valves and packing. Use of a Sundyne pump also eliminates the piping support systems needed to deal with vibrations of reciprocating pumps.

Sundyne pumps give similar reliability to conventional centrifugal pumps and are no more difficult to maintain than other single stage centrifugal pumps. Maintenance for multistage centrifugal pumps is much more expensive and difficult due to the considerably greater number of parts. Sundyne pumps, due to the high shaft speed, have a reduced seal and gearbox life compared to the lower speed centrifugal pumps. However, Sundyne has a gear box exchange program, both in the and , in which they send out a new gear box in exchange for a replacement in kind within two days of the request.

3.6 Sundyne Pump Curve

Generally, conventional centrifugal pump curves rise to shutoff. As the flow decreases, the head continuously rises. The same curve for Sundyne pumps is flatter and rises to 30% of design capacity and can then actually fall 5% to zero capacity. This creates a “hump” between 0 and 60% of capacity. The curve then falls only 10 percent from 60 to 100% range of capacity. Inflection Point Engineering does take credit for a flatter curve in revamps if the Sundyne pump is in place and if the pump curve is available. Also on new units if the estimated shutoff pressure with the 1.25 multiplier slightly exceeds a flange class break point a lower multiplier may be used. Consult a pump specialist.

A conventional single speed centrifugal pump has one design variable, the impeller diameter. Therefore, most often the rated process point is not at the pump’s ideal operating or best efficiency point (BEP). A Sundyne pump however, has three design variables; impeller diameter, outlet diffuser size and speed. The rated process point is typically at the pump’s BEP.

Turndown

It is not recommended to operate in the “hump” area between 0 and 60 percent of capacity described in Section 3.6. The pump can have two capacities for the same head and “hunt” between them. This can cause unstable operation. For this reason the minimum capacity of the pump is always 60% of rated flow. Per Section 3.6 the rated flow is typically at the pump’s BEP. Note that Sundyne also makes models that do not contain this characteristic hump. If this is desired to eliminate a potential spillback consult a pump specialist.

Sundyne’s do not automatically require spillbacks. However due to the high minimum flow requirement compared to most conventional pumps, most Sundyne’s do require a spillback for turndown flow.

Parallel Operation

Sundyne pumps can be operated in parallel. However due to the “hump” in the operating curve described in Section 3.6 it is not advisable to control two Sundyne pumps operating in parallel with a single control valve. It is necessary to have separate control valves with separate spillbacks so each pump capacity can be maintained above the minimum flow rate. This will keep each pump out of the range where there could be two capacities for one head.

For certain sizes, Sundyne can make a pump with a rising curve. Consult a pump specialist to see if a pump with a rising curve can be specified for a particular application, thus avoiding the need for separate control valves and spillbacks.

Special Requirements

Sundyne pumps have a Cl. 600 flange as a minimum.

Most Sundyne pumps have an internal cyclone separator for the seal flush. Therefore the pump calc tool will select an API Plan 31 if the pumping temperature is under 300˚ F and 41 if the pumping temperature is equal to or greater than 300˚ F. The exception is if the specific gravity is under 0.6. Then an API Plan 13 is selected. This is to avoid flashing in the cyclone separator.

Inflection Point Engineering accepts inducers on vertical pumps. Because of this Inflection Point Engineering accepts higher suction specific speeds on Sundynes than conventional pumps. Suction specific speeds on Sundynes can be as high as 24000 (US units).

3.10 Sunflo Pumps

Sunflo pumps:

• are a range of horizontal, high head, high speed pumps manufactured by Sundyne.
• could be specified instead of Sundyne pumps for non-flammable, non-toxic services such as water or caustic.
• are not built to API 610 standards so they more economical than Sundynes.
• can pump smaller capacities than Sundynes, down to about 6 gpm (1.4 m3/hr).

Do not use Sunflos on hydrocarbon.

The pump selection tool in hydraulics does not consider Sunflo pumps. A Sunflo should be considered for a non-hydrocarbon low flow, high head service where an ASME pump is not suitable. Consult a pump specialist to determine if a Sunflo is applicable.

Sunflo pumps are limited to 350 psig suction pressure, 300˚ F and 250 HP.