Glossary

Glossary

AGITATOR HEAD

The unit that drives and supports the agitation/mixing shaft. It is of utmost importance proper construction that only a wide experience can provide. The basic classification is according to the type of support of the agitation shaft.

IMPELLER

The impeller is the element that transmits the energy provided by the motor to the fluid. They can be basically of axial, radial or tangential flow. The choice of the suitable impeller is extremely important to achieve good results. With its more than 40 years of experience LINK INDUSTRIAL gives the necessary advice to ensure excellent results.

HIDROFOIL

The HIDROFOIL impeller is an in-house development by LINK INDUSTRIAL and actually becoming a standard for medium and large size agitators with intermediate viscosities in suspensions and mixtures. The curvature of the blades, designed to achieve a high hydraulic performance, allows in addition a low-cost and light-weight construction and the possibility to work in the subcritical region even at relatively high speeds. The two-bladed design facilitates assembly through the manhole and its longitudinal profile has been designed to minimize loads on the shaft during filling and emptying of the tank which means greater security and/or possibility of longer shafts with same diameter.

VERSAFOIL

The VERSAFOIL turbines are the recommended impellers for difficult tasks of agitation especially when the process goes through phases with varying viscosity. The design of the blades with their curved profile makes them insensitive to viscosity variations and achieves that axial flow remains constant over a wide area, thereby allowing a reduction of the number of turbines. Although its cost is relatively high, its selection is often the globally most economic option. A very uniform agitation in the whole vessel will be achieved, including with Non-Newtonian fluids. VERSAFOIL impellers are especially suitable for crystallization and heat transfer processes.

PROPELLER

Impeller for mainly axial flow. To achieve high volume flow rates at high number of revolutions. Propellers are sensitive to changes in fluid viscosity.

The axial pitch lies between one and two times the diameter. Agitators with propellers are used to maintain high vertical flow rates (e.g. to keep heavy particles in suspension).

DISPERSER DISC

Toothed disc for mainly radial flow. It is especially useful when intense shear forces are required, either in emulsions, for particle size reduction or disintegration of lumps.

PITCHED BLADE TURBINE

Impeller for axial-radial flow. Unlike the propellers the pitched blade turbine has a constant blade angle (typically 45°). Its most common applications are homogenization and solids suspension.

ANCHOR

Anchors generate a mainly tangential flow. They are suitable for dissolving and especially to achieve high heat transfer rates for highly viscous media.

DOUBLE FLOW

It is the former version of the VERSAFOIL impeller. It is still used for some applications.

HELICAL RIBBON

This type obtains a vertical movement of the fluid, which causes a quick mixing or an excellent heat transfer in the case of highly viscous liquids or granular solids.

SEALING

The design of the agitator head is essential for a successful sealing. The minimization of deformations is particularly important. This is especially considered by LINK INDUSTRIAL. The selection of the corresponding sealing (mechanical seal, lip seal, labyrinth seal or stuffing box) depends on the requirements of the process.

LIP SEAL

Lip seals are used for vessels under atmospheric pressure or slightly over-pressure, with a maximum temperature of 130ºC. Lip seals prevent that dirty water or foreign substances (dust etc.) enter the vessel or that vapors drain off.

STUFFING BOXES

Applicable for gauge pressures between -1 and 4 bar and for a maximum temperature of 200ºC.

Especially applicable for low speeds.

They can be equipped with a lantern for lubrication and cooling or double chamber for cooling.

A certain leakage of stuffing boxes (depending on application) is unavoidable.

The major benefit of this sealing is that it can be changed easily without disassembly of the agitator.

MECHANICAL SEALS

There are applications which require a mechanical seal, for example for processes under pressure or under vacuum as well as for aggressive media.
LINK INDUSTRIAL selects among the leading manufacturers of mechanical seals the most suitable seal for the corresponding application. Thus the cost/performance ratio will be optimized for each case.

If required by the process, the components of the seal, which are in direct contact with the vessel’s product, can consist of special materials, i.e. Hastelloy, 904L, ... or plastic materials (Polypropylene, PVC, Halar).

SINGLE-ACTING MECHANICAL SEAL

This type of seal is applicable for pressures from -1 to 15 bar, with a maximum operating temperature of 150ºC or 300ºC with cooling flange. Their use is limited by the maximum peripheral seal face velocity of about 2 m/s for vertical shaft installation.

They can be mounted internally or externally.

There are applications for chemical industry, pharmaceutical industry, food industry, cosmetics industry, paints industry,...

There is the possibility for FDA certification.

DOUBLE-ACTING MECHANICAL SEAL

Suitable for high pressures or very aggressive products. You may go to high face speeds.

A buffer fluid, which has to be compatible with the vessel’s product, is required. Provided that the product is non abrasive, the product itself could be used as the buffer fluid.

In the case of external lubrication, the buffer fluid has to be maintained at a pressure 1 bar above the pressure in the vessel.

GAS MECHANICAL SEAL

The gas mechanical seals are mainly applicable for sterile processes in pharmaceutical industry.

One of the major advantages is the possibility to use a pure or a sterile gas like for example nitrogen, air or vapor.

A distinction is made between seals with and without contact:

  • A gas mechanical seal with contact is a double-acting, dry-running mechanical seal where the buffer fluid is a gas.
  • In case of gas mechanical seal without contact the two seal faces remain slightly separated, which implies certain buffer gas consumption. However there is nearly no wear. This ensures the absence of contamination of wear particles from the seal faces into the vessel’s product.

MAGNETIC COUPLINGS

A magnetic coupling can be used for high process pressures without the need for any auxiliary system.

The use of a magnetic coupling is required whenever absolute leak tightness has to be guaranteed, for example for toxic or dangerous products.

C/ Alt, 25
Polígono Industrial Ca n'Alzamora
08191 Rubí ( Barcelona)
Tel. +34 935 862 300
Fax. +34 935 862 301
eMail info@linkindustrial.es