Purpose and characteristics of the fan

Model  4-73 centrifugal fan is generally used for forging furnace and high pressure forced ventilation, widely used for materiel delivery and suitable to delivery air and gas of non-corrosion, non self-burn and free of viscous material. The temperature of the delivered medium shall normally not exceed 250℃(not exceed 300℃maximum), the dust contained in the medium and hard-fine particle shall not be bigger than 150mg/m3. This series of fans in addition to the above characteristics,but also has high efficiency, low noise, large flow adjustment range, flat performance curve and so on. Fan three high degree of versatility, good versatility, wide range of application.

Type of fan

1. The fan is made as a single suction and its driving is A type. There are more than 20 types of fan numbers which are 3、3.15、4、4.5、5、5.6、6.3、7.1、8、9、10、11.2、12、12.5、14、16、18、and 20.

2. The fan can be made of 2 types of rotation i.e, right and left. Viewing from one end of the motor, it is called as clock-wise fan if the impeller rotates clock-wise, shown as “right”, On the contrary, it is called as counter-clock-wise fan if the impeller rotates counter-clock-wise, shown as “left”.

3. The outlet position of the fan can be expressed from the outlet angle of the casing. It can be made 7 kinds of angles which are 0°, 45°,90°, 135°,180°,225°, 270°，from both “Right” and “left”.

4. There are 4 driving modes: A,B, C, D:

A—Shaft disc of fan is installed on motor shaft by keyway, i.e. motor directly connecting;  

B—Cantilever bearing unit, belt driving, pulley is in the middle of two bearings;

C—Cantilever bearing unit, belt driving, but the pulley is outside the bearing;

D—Cantilever bearing unit, coupling directly driving.

Structure of the fan

№3-7.1 fan mainly consists of impeller, casing and inlet. №7.1- above fan mainly consists of impeller, casing inlet and Driving unit.

Casing: to be welded into a volute with normal steel plate.

Impeller: The fan has 20 forward-curved blades. The maximum circumference speed of impeller diffuser shall not exceed 140m/s. The impeller, after being shaped, shall be balanced statically and dynamicaly and thus it guarantees a smooth operation.

Inlet: to be integrated into a convergent streamlined structure and bolted on the front cover.

Driving unit—it consists of shaft, bearing box, rolling bearing, belt pulley or coupling.

See the attached drawing for installation and overall dimension.

Performance and selection of the fan

Performance of the fan:The performance of the fan is expressed by the parameters of fan flow, full pressure, spindle speed, shaft power and so on. Performance curve and the performance of the performance given in the table. Blower performance: When ordering the performance table shall prevail. Fan performance test total pressure value of 5% of the total pressure deviation is less than design value.

Such as fan using condition does not accord with the above, the performance shall be carried out according to the related formula conversion.

When excessive or insufficient flow of processing. When use, often occur the phenomenon of excessive or insufficient flow, produce a lot of reasons for this phenomenon, if it is in use process flow occurs when small phenomenon, is mainly due to the resistance of pipe network. If it is in use process, after a long time to reduce gradually, mainly due to network congestion.

After the fan is a new installation, a formal operation occurs when the flow phenomenon of excessive or insufficient reason mainly has the following points:

1、The actual value and calculating value difference is too large in the resistance of pipelines.

By the general network characteristic equation: P = Kq, type of K - drag coefficient.

If the actual value K is less than the calculated value K, increases the flow, if the actual value is greater than the calculated value K K, the flow decreases.

2、When the choice is not the fan itself fully considering the influence of the pressure deviation of P, when fan actual total pressure for positive deviation, then the flow; Negative deviation, the flow rate decreases.

Began formal operation after fan is a new installation, or in use process flow is too big or too hours, one of the following methods can be used to eliminate the;

Make use of the fan speed adjusting flow increase or decrease.

Using the new high or low pressure switch to increase or decrease in flow rate of fan.

Change the pipeline resistance coefficient K to change traffic.

At this time to try to change the network reduce drag coefficient to increase traffic, also can increase the fan rotation speed and changing the high pressure fan, but speed shall not be greater than the maximum speed performance table.

Installation and use of fan

 

9-19 type fan only gives the non-dimensional performance table of №10 sample fan (see table1). The dimensional performance of the fan can be calculated with given non-dimensional performance table.

The dimensional parameter formula is calculated with non-dimensional

parameter.

If it is in non-standard state when operating, the performance of non-standard standard state must be converted to the performance of standard state. And then select fan according to the converted performance. The converting formula is as follows:

           

     

Installation and operation of the fan

Before installation: Check all components of the fan to see weather any thing is missed; weather the impeller rotates in the same direction as the casing; weather all components are connected tightly and weather the impeller rotates freely.

During installation: Pay attention to check the casing and any tools or goods should not be dropped and remained inside the casing. The connecting face between the support of the fan and the foundation or between pads and foundation should be tight. Adjusting should be made to joint the fan with foundation surface and to connect the fan with suction, discharge duct naturally. Forced assembling, especially, applying weight of pipes on any components of the fan isimpermissible. Also, attention shall be paid to the horizontality of the fan.

Requirement of installation:
(1) Install the fan according to the position and sizes shown on the drawing. To

insure high efficiency, radial and axial clearances between inlet and impeller must be guaranteed.

(2) After installation, turn, with a little force, the driving rotor to see if it is over

tight or touched with stationary components.

(3) Commission Can only be carried out after the unit is through the final

inspection. In order to prevent the motor being burnt out due to overloading, the fan

can only be started up and tested without loading. If the case is ok, increase the load

step by step until the rated operating condition is reached. Control the current strictly

during operation to prevent it exceeding the rated value.

Operation of the fan:

 (1) Before starting-up, the following preparations shall be made:

a) Close the valve of suction pipe and open a little the valve on discharge pipe.

b) Check the rotating and non –rotating parts to prevent colliding and friction.

(2) After the fan is started-up and the normal speed is reached, check the bearing temperature is normal or not during the operation. If there is no special requirement for bearing temperature, the temperature rise of the bearing shall not exceed 40℃of surrounding temperature. The value of even root vibration speed of the bearing shall comply with the following rules: rigid support(support is fixed on the foundation) Vrms≤4.6mm/s; flexible support(be set onfoundation or floor through absorber) Vrms≤7.1mm/s. In case that severe vibration, colliding, quick rise of bearing temperature and other abnormal phenomena are found, stop the fan immediately.

Maintenance of the fan

1) Cautions in fan maintenance:

①The fan can only be put into operation in normal condition.
②When the fan is started-up after inspection, attention should be paid to see

weather each component is ok or not.

③Check periodically the dust and contamination inside the fan to prevent rust.

④Maintenance can be carried out during shut down of fan to assure operators

safety

2) Cautions in normal operation of the fan

①During the star-up, shut-down or operation of the fan, if some abnormal thing

happens, inspections shall be carried out immediately; if it is small failure, the reason shall be checked out and eliminated, if it is a big failure, the fan shall be stopped and inspection and maintenance shall be made immediately.

②Replace lubricant grease of motor bearing according to the real condition.

The main failure and reason of the fan

1) severe vibration of the fan

①friction between casing (or suction unit)and impeller.

②Foundation is not rigid enough or firm enough.
③loosing of rivets in impeller or deformation of impeller.
④Loose match of shaft with impeller disc
⑤Loose of connecting bolts between casing and support, and between motor and

support.

⑥The installation of inlet and outlet ducts is improper which causes the casing

deformation and resonance.

⑦Rotor unbalance caused by dust, contamination on blades, wear of blades,

deformation of impeller and bending of shaft.
2) High rise of bearing temperature
①severe vibration

②lubricant is poor in quality, deteriorated, mixed with dust, sand, contamination

and etc, or insufficient in quantity.

③Wornout of rolling bearing
3) Overcurrent and high temperature rise in motor.
①The valves on inlet and outlet pipes are not closed completely when starting-up.

②Input voltage is low or a single phase of power supply is cot out.
③Influence caused by severe vibration
④The speed of main shaft is bigger than the rated value.

Supply scope of fan unit

One fan, one driving motor and 4 sets of foundation bolts

Purchase information

1）when purchasing, indicate the size, speed, flow, pressure, discharge angle and rotating direction of the fan, and the model, power, and speed of the motor.

2）Also, indication shall be made clearly when ordering, if you need inlet filter, silencer, inlet and outlet soft connection, vibration absorbing platform and vibration absorber.

Huashide(shandong)fan Co.，Ltd

Http:www.hsdfans.com

Add:kunmingrod.linyi.P.R.china

E-mail:17853928877@163.com

Tel: 17853928877