Caprari PM Series High Pressure Horizontal Multistage Pumps

Horizontal multistage pumps for pressures up to 100 bar

The Caprari PM series is a range of multistage centrifugal pumps with horizontal shaft for high-pressure water duties. The catalogue (code 996440M/08-26) lists eight sizes from DNm 50 to DNm 150 with operating pressure of up to 100 bar and flow rates up to 160 l/s. Two designs are offered, PM.2P and PM.4P, optimised for 2-pole and 4-pole drives, with a maximum rotational speed of 3,500 rpm and 1,750 rpm respectively.

The pump is driven through an elastic or a fluid coupling and rotates clockwise as seen from the drive side. Construction is a suction casing with positionable inlet, intermediate stages with diffusers carrying renewable wear rings and radial impellers with axial thrust compensation, and a delivery casing with mounting feet and an upward-pointing outlet. A completely protected stainless steel shaft runs in two stiff, grease-lubricated ball bearings and four external tie bolts clamp the stages. The catalogue main uses are water conveying in industrial and civil systems and pipelines, artificial snow, fire-fighting service, pressure boosting, irrigation and desalination.

Technical specification

Materials (PMH and PMS versions as listed)

Screws and nuts are stainless steel. Special packing glands are available on request for all sizes.

Ordering, options and drive notes

The code reads PM, S for nodular delivery casing and shells or H for high pressure, T for mechanical seals, then 2P or 4P, the delivery nominal diameter, the number of stages and the impeller trimming. Executions on demand include A (anticlockwise rotation with shaft projection on the delivery side), D (double shaft end), H (bronze impellers with stainless keys), L or M (suction port pointing up or to the left), and B (special gland packing for high pressure, standard on PMH).

The catalogue stresses that the maximum permissible power P2 max depends on the number of impellers and the speed; the example given is PM100 at 2,965 rpm with a factor of 0.08 per rpm giving 237 kW, so check the absorbed power against that limit. Standard motor shaft heights follow UNI 2946 and ISO 496, and the catalogue carries a motor data table (starts per hour, voltage variation, moment of inertia). When the pump is driven by an internal combustion engine, a clutch is advised.

Key features from the catalogue

The catalogue lists several construction points. The stages are clamped by four external tie bolts and carry renewable wear rings on the diffusers. Radial impellers are fitted with axial thrust compensation, the shaft is completely protected in stainless steel, and it runs in two stiff ball bearings lubricated with grease. The outlet points upward on the delivery casing, and the suction casing inlet can be positioned. Rotation is clockwise as seen from the drive side, and the pump is driven through an elastic or a fluid coupling.

Run-time with a closed port depends on the speed and temperature, from 2 minutes at 3,500 rpm to 6 minutes at 1,450 rpm at 40 C, so avoid starting against a closed valve on automatic plants.

Selection and installation notes

Select a pump from the duty point: the flow, the head, the liquid and its temperature, the supply voltage and the expected operating hours. Check the electrical supply and cable size against the motor rating, install the pump as the manual shows on a firm base with pipework that does not strain the ports, protect the motor against overload and dry running, and fit non-return and isolation valves in the delivery line. Keep the installation and commissioning record, and plan routine inspection of seals, bearings and wear parts.

For high-pressure service, confirm the pressure rating of the pipework, valves and supports, and fit pressure relief to protect the system.

Information needed for a quotation

Send the full model code, the quantity, the delivery location in Oman or the GCC, the intended use and any accessories needed, so that the complete package can be quoted together.

Documents and supply information

The manufacturer data sheet is attached to this page and should be read together with the project specification and the site risk assessment before a purchase is confirmed. Ratings, standards and dimensions are quoted as printed on that sheet. Lead time, stock position and certificates available with the shipment are confirmed in the quotation, and we supply to Oman and the wider GCC region for industrial, utility and building services projects.

Where the PM fits in GCC schemes

High-pressure multistage pumps are used for desalination feed and booster duty, high-rise and district supply boosting, fire-fighting and pipeline transfer, and large irrigation. A closed port should be avoided for more than a few minutes, and with liquid at 90 C no closed-port running time is allowed, so a minimum-flow line is needed on hot service. The catalogue lists clean fresh water; seawater duty is not stated, so ask Caprari for materials on seawater or brine.

The catalogue prints no fire-pump (UL, FM, EN 12845), ATEX or API approvals for the PM series, so none is claimed. The official catalogue is attached. Related pumps are listed under pumps. Seven Star LLC is an independent supplier in Muscat: send flow, head, suction pressure, liquid temperature and drive and we will confirm the size, stages and version against the Caprari catalogue before quoting.