IS 4894 FOR CENTRIFUGAL FAN PDF

Comments. IS Code. Recent; Popular; Featured. IS – – Pallets for materials. Buy BIS IS (R) SPECIFICATION FOR CENTRIFUGAL FANS from SAI Global. Standard Air. Centrifugal fans for use in mines and hazardous atmospheres may requirt: additional requirements to be met, not covered by this standard.

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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. This is also commonly known as wheel diameter. Part of Motor or Rboulatob Class A Class E Tbmpbbatukh-Risb, “C Method OF Mbasu- BBMBNT 6 Change of resi- stance Change of resi- stance Insula- tion 3 60 60 Insula- tion 4 75 75 Fir B Insula- tion 5 80 80 The temperature-rise shall not reach such a value that there is a risk of injury to any insulating material on adjacent parts of the regulator 40 40 40 Thermo- meter Thermo- meter 1 2 i] Insulated win- dings of motors ii Insulated wrin- dings, if any, of regulator with conti- nuous runn- ing on any contact iii Regulator resi- stance unit with conti- nuous runn- ing on any contact iv External surfa- ces likely to be touched during normal usage Note 1 — The thermocouples, if used, should be applied only to external surfaces which may be reached by an ordinary thermometer.

The stray load loss is assumed to be percent of the shaft power. The test voltage shall be applied as follows: A system resistance line shall also be fna, passing through the specified duty point cenrifugal that the total or static pressure varies with the square of the inlet volume flow see Fig. These are intended to prove general quali- ties and design of given type of fan.

In the case of a double insulated fan, both basically insulated parts and live parts shall not be accessible to the standard test finger. The most probable operating point for the fan shall ror at the intersection of the fan characteri- stic and the system resistance line.

The ‘Running’ and ‘OFF’ positions of the regulator shall be distinctly and clearly marked and the indicator on the cnetrifugal handle or knob shall correctly indicate the position of the regulator.

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IS – – Centrifugal fans | QuestIn

If the number of defectives found in the first sample is less than the rejection number, take a second sample of size indicated in col 3; and if the total number of defectives in the first and second van put together is less than the rejection number, accept the lot, otherwise not. This test shall be carried out with the guard if any, in position.

If more convenient, the flare may be remo- ved for the test. While taking the current and watt read- ings during these tests, however, the voltage shall be maintained at the test voltage. This value shall fall within the range of specified tolerances. The guards shall be securely attached and shall be adequately rigid to resist accidental contact with the blades. For Reynolds numbers of and above, the coeffi- cient of discharge is 0″ and will cover the majority of fan tests.

Part 55 Electric fans. The openings – shall be flush with the duct and free from burrs and countersinks. However, if regulators are required, this shall be a matter of agreement between the purchaser and the supplier.

If the fan is specified for two or more distinct rated voltages with three or more supply terminals, the tests shall be carried out at the most unfavourable voltage. These insulat- ing materials are detailed in IS: The criterion of noise level may, therefore, be subject to an agreement between the manufac- turer and the purchaser. Such an addition shall then be regar- ded as a part of the fan.

Full text of “IS Centrifugal fans”

The inlet airway diameter D used in the computation shall be measured after- manufacture. All metallic parts associated with it shall be protected from accidental contact. Capacitors shall comply with IS: Intermediate values of d, may be obtained by linear interpolation. 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.

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: When the guards are in two pieces, positive locking arrangement to keep the two pieces together should be made. Note — Nevertheless, fans made for other freque- ncies shall be considered to comply with the specifica- tion provided they do so in all other relevant respects.

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The resistance measurement shall be made with a current of lOA with a dc voltage not exceeding 6V. In the case of indirectly driven fans, the electric motor shall conform to the relevant Indian Standard, 1.

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. A recommended sampling plan is given in Table 3. The value to be adopted for the temperature of the cooling air during a test shall be the mean of the readings of the thermometers taken at equal intervals of time during the last quarter of the duration of the test.

Centrifugal fans [ETD 5: 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. It is positive when above and negative when below the ambi- ent pressure. Note — The trade name, voltage and the size of the fan shall be marked on associated regulator.

Part 1 Methods of testing performance’, issued by the British Stand- fann Institution. Such fans shall be specially marked. The following additional information in respect of an electric centrifugal fan shall be supplied by the manufacturer on request: Full text of ” IS Never- theless, fans made to work in cenrifugal cooling air tem- peratures may be regarded as complying with this specification provided the temperature-rise values are reduced corresponding to the increase in cooling air temperature.

It is always positive.

IS 4894: Centrifugal fans

As type test, this test should preferably be done immediately after the temperature-rise test. The fixed losses and copper losses shall be calculated in accordance with the details given in IS: This requirement is applicable for all positions in the normal use.

The method of measurement of the speed of fan shall be centtrifugal that the speed of the fan is not appreci- ably affected. Note — The need for specifying limits of noise levels acoustical of the fans is recognized.