7GEA Wiegand GmbH 76275 Ettlingen Germany Tel.: +49 7243 705-0www.gea-wiegand.com Fax: +49 7243 705-330 E-mail: info.gewi.de@geagroup.com

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General information on jet pumps

Jet pumps, also referred to as ejectors, are devices for the conveyance, compression or mixing of gases, vapours, liquids or solids in which a gaseous or liquid medium serves as the motive force. They operate by the con-version of pressure energy into velocity in suitable nozzles. They are pumps without moving parts.The basic principle of jet pumps consists in the liquid or gas jet being emitted by a noz-zle at high speed entraining and accelerating the surrounding liquid, gas or solid matter. The result of this action is a mixture of the driving and entrained (sucked) fluids, the velocity of which is reduced and the pres-sure increased in a second nozzle.

The practical application of this principle requires a simple apparatus which essential-ly consists of only 3 main parts (figure 1): motive nozzle (1) diffuser (2) head (3)

The flow channel of the diffuser consists of a part converging in the direction of the flow (the inlet cone), a cylindrical piece (the throat) and a diverging part (the out-let cone). The pressures at the connections and the corresponding mass flows determine the functional effect of a jet pump.

A jet pump is provided with at least 3 con-nections (figure 1): motive medium inlet connection (A) suction manifold (B) pressure manifold (C)

The pressures prevailing there are as follows (figure 2):p1 pressure upstream of the motive nozzle =

motive medium pressurep0 pressure at the suction manifold = suction pressurep pressure at the outlet manifold = discharge pressure

The mass flows 1, 0 and for the enter-ing and exiting fluids are measured in kg/h. For this purpose, the following equation shall apply: 1 + 0 = .

For the relationship between the various pressures, no simple rule can be applied. The internal processes in jet pumps are complex and only in a limited way accessible by cal-culation.

FiG. 1

FiG. 2

DEsiGnaTions oF jET pumps

The terms of jet pumps (ejectors) are defined in DIN 24290. According to DIN 24290, jet pumps are named according to the motive side and to the suction side. The designations in this catalogue follow this standard.

AccordinG to tHE

suction sidE

AccordinG to tHE motivE sidE

GAs jEt pump stEAm jEt pump Liquid jEt pump

Jet ventilator Gas jet ventilator Steam jet ventilator Liquid jet ventilator

Jet compressor Gas jet compressor Steam jet compressor

(Vapour recompressor)

Liquid jet compressor

Jet vacuum pump Gas jet vacuum pump Steam jet vacuum pump Liquid jet vacuum pump

Jet liquid pump Gas jet liquid pump Steam jet liquid pump Liquid jet liquid pump

Jet solids pump Gas jet solids pump Steam jet solids pump Liquid jet solids pump

The designation of the individual parts of a jet pumps is standardized according to DIN 24 291.

GEA Wiegand GmbH 76275 Ettlingen Germany Tel.: +49 7243 705-0www.gea-wiegand.com Fax: +49 7243 705-330 E-mail: info.gewi.de@geagroup.com

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General information on jet pumps

scopE oF DElivEry

The scope of delivery of the jet pumps department of GEA Wiegand is divided into two main fields.

1) dELivEry of stAndArd AppArAtusEs

This catalogue gives a wide selection. The types and sizes are selected such that for usual tasks a suitable unit can always be found. Description and capacity curves and the corresponding sheets allow the correct choice.

2) dEsiGn, construction And dELivEry of

spEciAL AppArAtusEs And pLAnts

For this purpose our well-trained staff of spe-cialists in jet pumps and vacuum systems is available. In our modern Research Labora-tory, the required analyses, research work and tests are carried out. Special leaflets give detailed information; they show the gener-al principles of these plants and inform the customers which data are needed for engi-neering and for the preparation of a quota-

tion. Jet pumps can be built for very small as well as for extraordinarily large capacities. They can be constructed from most differ-ent materials and stand out for the follow-ing features:

Reliability Simplicity Low maintenance costs Low acquisition costs

WhaT has To bE bornE in minD?

WHEn purcHAsinG jEt pumps AccordinG to tHE

cAtALoGuE:

The capacities specified in the catalogue

sheets are only approximate values. They will be different if operating conditions change.

For the design in individual cases, our order confirmation is binding and not the catalogue sheet.

Where necessary, installation and operat-ing instructions are made available.

Normally, cast apparatuses are supplied with flanges bored to DIN PN 10, unless otherwise agreed. If specified, flang-es according to ASME, BS or other spe-cial flanges can be supplied, if the cast-ing model is available or if it is a question of welded (fabricated) apparatus. Counter flanges together with seals and screws are only supplied on request.

Our General Sales Conditions are valid for all supplies.

WHEn instALLinG jEt pumps:

Do not mix up connections.

Connecting pipe lines must be of equal or larger diameter than the corresponding connections on the plant.

Valves, fittings, seals etc. must have the full cross sectional area and not restrict the line.

For longer pipe lines, the cross sectional area must be larger to obtain the lowest possible pressure loss. In all cases, care must be taken to ensure that the pipe line be constructed with the most favourable flow characteristics.

Steam lines should be well insulated. Dry motive steam is particularly important for the good operation of steam jet vacuum pumps.

Before the first start-up the lines should be blasted and cleaned with steam or com-pressed air. Otherwise, rust, dirt and weld-ing beads can easily block the nozzles of the pumps.

Furthermore, we recommend the installa-tion of a dirt trap in the supply lines for motive fluids.

For further details on the assembly and operation of jet pumps please refer to the respective operation instructions.