Fan Mechanical Running Test

This content provides you with a sample fan mechanical running test procedure in the manufacturing vendor shop. This article is a supplementary article for fan and blower inspection article. You may also review fan and blower inspection and test plan. 

Fan Mechanical Running Test Procedure

1. Scope and Field of Application

The present operative instruction has the scope to define the operating modalities and acceptance criteria for the running test of fan.

2. Reference

• ISO 10816-3: Mechanical vibration - Evaluation of machine vibration by measurement on non rotating parts;
• ISO 2372: Mechanical vibration of machines with operating speed from 10 to 200 rev/s
• API 617:Axial and centrifugal compressors and expander-compressor for petroleum, chemical and gas industry services

3. Definitions

Mechanical Functional Test:

for fan (running test): functional test of rotating machine performed at settled value of rpm. It is carried out the bearings vibration measure as well as, the bearings temperature.

4. Responsibilities

The Quality Control operator (QC) must:

• Perform the mechanical functional test;
• Issue the test certificate;

The Technical manager (TM) must:

• When requested, co-operate with QC during test;
• Define the operating conditions for fans running test.

The Quality Assurance manager (QAM) must verify the right test execution.

Operative Conditions

Fan Mechanical Running Test - Test Limits

The test technical limits for fans running test are:

• With absorbed electric power ≤ 200 kW and starting current ≤ 190 A, with fan inlet closed, it is possible to test the fan at the operating speed;
• Test will be carried out with job motor
• Voltage 0 - 400 V three phase;
• Frequency 50 Hz for direct on line starting, from 5 to 100 Hz for variable speed starting (inverter).

Operating Conditions

Fan is tested in the following conditions:

• Fixed to suitable base frame on the ground floor
• The fan speed will be selected according to contractual conditions as well as test limits.
• Fan speed will be the design one.
• The positions for bearings vibration and temperature measurement are selected according to following:

Impeller Arrangement: assembled on shaft with supports

Vibration: On the support casing in correspondence of two bearings

Temperature: On the support casing in correspondence of two bearings

Fan Mechanical Running Test - Test Execution

The fan is put into operation according to above design conditions.

The test time has been established in 120 minutes .

Before start up , the free and right sense of rotation of impeller must be checked.

During test , for each measurement positions , the following measures are carried out:

• Horizontal Vibrations In Correspondence Of Axis Of Rotation; The Global Value (Using Filter According To ISO 2372) Will Be Measured in RMS Mm/Sec.
• Motor Speed Measured in RPM.

In the test will be measured :

• Vertical Vibrations in Correspondence of Axis Of Rotation; The Global Value (Using Filter According To ISO 2372) Will Be Measured In RMS Mm/Sec.
• Bearings Temperature and Ambient Temperature;
• Feeding Voltage (By Read-Out On Electric Panel Display);
• Motor Absorbed Current (By Read-Out On Electric Panel Display);

At the end of mechanical functional test with positive results, QC will file the test data and sign the relevant step on workshop time sheet.

5. Acceptance Criteria

Vibrations

Vibration measured in velocity RMS mm/s in the 10 to 1000 Hz range are considered acceptable when the following data are satisfied:

• Fan on rigid supports: < 2.8 mm/s RMS ; according to 2.6.8.8 of API 617.

It is possible convert the RMS-velocity values to peak-displacement amplitudes according to the formula:

Pk = 0.225 Vf/f

Vf = RMS Value of the Vibration Velocity (mm/s) at the frequency f

f = Vibration Frequency (Hz)

Pk= Peak-Displacement Amplitude

Temperature

For grease lubricated bearings, temperature values equal or less than 70°C are acceptable, measured with ambient temperature of 20 °C. In any case ∆T of 50 °C will be applicable also for ambient temperature less or upper than 20 °C.

Any different temperature value upper the foreseen one shall be evaluated.

6. Measuring Equipment for Fan Mechanical Running Test

The described test shall be performed , where requested, using calibrated equipment.The instrumentation to be used consists in :

• Vibration analyzer
• Digital thermometer

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