In every position, the disc is radially and axially balanced. There are no radial components which could detach the disc or press it against the casing; therefore, the liquid does not tend to escape. The resultant pressure force is the same in any position so that the amount of power absorbed is always uniform.

elastic device The elastic device acts like a spring by keeping the disc in grazing contact with the cylindrical walls of the casing, thus creating an elastic coupling between the central bearing of the disc and the shaft. The device allows pumping disc to run over small solid particles like a car wheel which bounces on its suspensions when it runs over a stone; it also compensates for wear on parts and makes the pumping system insensitive even to high temperature changes by compensating for expansion.

viscosity and temperature

The U model pumps are suitable for liquids with any viscosity and for pumping temperatures of 250°C and over.

operating speed

O.M.G. rotary pumps are designed according to high standards of reliability and quality: therefore, they normally run at low r.p.m. Although limited speed of rotation necessarily involves larger sizes of pumps and higher costs, it is the best guarantee of safety, efficiency, regular operation and, above all, long service life.

operating features

strictly volumetric:
with constant, uniform and, within certain limits, independent flow over a wide range of fluid viscosities.

self-priming:
NPSH required less than 0.3 kg/cm² abs.; operates efficiently even under difficult suction conditions and when suction lift is considerable; no foot valve is needed.

reversible:
by operating the pump in the opposite direction, the direction of the flow is reversed; the liquid can therefore be pumped in either direction.

high performance:
mechanical efficiency over 85%, hydraulic efficiency over 90%, total efficiency over 80%, over a wide range of uses; low energy consumption.

simple and strong:
there are only two moving parts, the pumping disc and the shaft; the total number of parts is kept down to an absolute minimum and all parts are designed for high efficiency even under the most difficult operating conditions.

accessibility:
once the cover is removed, all parts of the pump are immediately accessible; there is no need to remove the pump from its base nor to disconnect the pipe flanges.

field of application

O.M.G. hollow disc rotary pumps are typically used to transfer:

• heavy, thick and viscous liquids; fuel oils, mineral oils, grease, resins, molasses and sugar syrups, bitumen, soap, inks and plasticizers.
• fluid, crude and volatile liquids; solvents, engine fuels, diesel oil, alcohols and fatty acids.
• delicate liquids: vegetable oils, foodstuffs, acetovinylic dispersions and emulsions.

direction of rotation

Generally speaking, both directions of rotation can be selected since the pumps are reversible. For the purposes of standardization a counterclockwise direction of rotation, as seen from the drive end, has been defined as normal, therefore the suction port is on the left, looking from the same side.
Suction and delivery ports can be reversed by reversing the direction of rotation, but, when a one-way safety valve is fitted, it must be reversed too.
To use the pumps in both directions, a two-way, double safety valve can be fitted.

construction materials

For parts that come into direct contact with the liquid, the normal construction materials used include:

• for the casing: cast iron, nodular cast iron, bronze, stainless steel
• for the hollow disc and pump shaft: steel, Cr-Ni steel, stainless steel

Other special materials can be furnished on request, though there are limitations due to the mechanical characteristics required by the materials.
Our technical department, with over 80 years of experience, with a wide range of different applications, can provide the customer with expert advice regarding the most reliable materials, for use in any given situation.

stuffing box

The seal in the shaft is normally created by means of a stuffing box designed to contain five or more square section packing rings. Many types of special packings are also available depending on the characteristics of the liquid pumped.

mechanical seal

All types of mechanical seals can be installed, on request, to meet any requirement. Normally, only mechanical seals produced by leading companies are supplied, in accordance with API standards. As an alternative:

• simple, internal mechanical seals, installed before the pump shaft journal bearing; the seal does not come in contact with the pumped liquid; according to API plan 02 or plan 11
• simple, external mechanical seals, installed after the pump shaft journal bearing; according to API plan 02, plan 11 and plan 62
• double, external mechanical seals, installed after the pump shaft journal bearing; according to API plan 33

couplings

The pumps can be supplied:

• with a free shaft, for direct operation at the speeds indicated in table A, or with a speed reducer mounted on the pump support
• on a single base, coupled by means of a reducer and a flexible coupling to electric, internal combustion, diesel or hydraulic motors
• on a truck wheel tyres