IS 4894 FOR CENTRIFUGAL FAN PDF

Zujinn When the guards are in fkr pieces, positive centrifgal arrangement to keep the two pieces together should be made. The screen may be composed of one or more layers of even wire or iiabric supported by a wire guard. Such fans shall be specially marked. The absolute pressure of the ambient atmosphere is the barometric pressure. A system resistance line shall also be drawn, passing through the specified duty point such that the total or static pressure varies with the square of the inlet volume flow see Fig. All metallic parts associated with it shall be protected from accidental contact.

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Zujinn When the guards are in fkr pieces, positive centrifgal arrangement to keep the two pieces together should be made.

The screen may be composed of one or more layers of even wire or iiabric supported by a wire guard. Such fans shall be specially marked. The absolute pressure of the ambient atmosphere is the barometric pressure. A system resistance line shall also be drawn, passing through the specified duty point such that the total or static pressure varies with the square of the inlet volume flow see Fig. All metallic parts associated with it shall be protected from accidental contact.

Note — The need for specifying limits of noise levels acoustical of the fans is recognized. The amendments issued to the previous edition of the standard have also been incorporated in this revision. It is positive when above and negative when below the ambi- ent pressure. The criterion of noise level may, therefore, be subject to an agreement between the manufac- turer and the purchaser.

In case of doubt, the tests shall be carried out at all voltages. When the air flow, in cubic tor per hour, is numeri- cally less than 16 times the airway diameter in metres, then the coefficient of discharge shall be taken appropriate to the Reynolds number given in Table 2. In the case of fans for use on three-phase, two separate earthing terminals shall be provided.

This test shall be fog out with the guard if any, in position. Note — The trade name, voltage and the size of the fan shall be marked on associated regulator.

Note — The difference in pressures is the mean pressure when facing tube reading is employed. Details of conditions under which a licence for the use of the Standard Mark may be granted to manufacturers or producersmay be obtained from the Bureau of Indian Standards.

The other limbs of the manometer shall be opened to the ambient atmosphere and the manometer reading shall be taken as equal to the average static pressure in the airway. IS Centrifugal fans In the case of inductance type regulator, it is essential that no portion of the inductive winding should remain permanently short-circuited in any of the running positions. Centrifugal fans [ETD 5: Such an addition shall then be regar- ded as a part of the fan.

This revision has been undertaken to take into account the experience gained since then and to align some of the safety requirements with the provisions of IS: The fixed losses and copper losses shall be calculated in accordance with the details given in IS: As type test, this test should preferably be done immediately after the temperature-rise test. Note — Nevertheless, fans made for other freque- ncies shall centrrifugal considered to comply with the specifica- tion provided they do so in all other relevant respects.

However, it has not been found possible to specify these limits at present on account of: It is always positive. The guards shall be securely attached and shall be adequately rigid to resist accidental contact with the blades. The inlet airway diameter D used in centrivugal computation shall be measured after- manufacture.

If the fan is specified for two or more distinct rated voltages with three or more supply terminals, the tests shall be foe out at the most unfavourable voltage.

The Standard Mark on products covered by an Indian Standard conveys the assurance that they have been produced to comply with the requirements of that standard under a well-defined system of inspection, testing and quality control which is devised and super- vised by BIS and operated by the producer.

These insulat- ing materials are detailed in IS: The most probable operating point for the fan shall be at centrirugal intersection of the fan characteri- stic and the system resistance line. The resistance measurement shall be made with a current of lOA with a dc voltage not exceeding 6V. The method of measurement of the speed of fan shall be such that the speed of the fan is not appreci- ably affected.

This is normally shown in graphical fashion, following performance tests carried out in accordance with The test voltage shall be applied as follows: A fan with protective electrical insulation may be of all-insulated construction or have either double insulation or reinforced insulation. In the case of indirectly driven fans, the electric motor shall conform to the relevant Indian Standard, 1. Search the history of over billion web pages on the Internet.

Capacitors shall comply with IS: The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. TOP Related Posts.

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IS 4894: Centrifugal fans

Sg; 5? The amendments issued to the previous edition of the standard have also been incorporated in this revision. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. SCOPE 1.

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IS 4894 FOR CENTRIFUGAL FAN PDF

Vudom The test voltage shall be applied as follows: The other limbs of the manometer shall be opened to the ambient atmosphere and the manometer reading shall be taken as equal to the average static pressure in the airway. This test shall be carried out with the guard if any, in position. The difference between the inlet volume centrifugaal at the intersection and the specified inlet volume flow that is, the duty point shall be cebtrifugal as the measure of departure of the fan from the specified perfor- mance. IS Centrifugal fans When the air flow, in cubic metres per hour, is numeri- cally less than 16 times the airway diameter in metres, then the coefficient of discharge shall be taken appropriate to the Reynolds number given in Table 2. It is positive when above and negative when below the ambi- ent pressure. In the case of fans for use on three-phase, two separate earthing terminals shall be provided. This is also commonly known as wheel diameter.

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