# Air compressor

###### tags: `lab-equipment`

## Technical specifications
### Specifications of screw air compressor

1) Type of air compressor- Screw air compressor, VFD, direct drive, permanent magnet or 2poles/4 pole IP55 protection preferred.
2) Duty cycle - continuous
3) Type of mounting- base or tank mounting
4) Number of stages for compression - single/ double
5) cooling system- air cooled
6) lubricant type-oil lubricants
7) after cooler - with
8) moister separator-with
9) oil separator-with
10) oil cooler-with
11) air filter-with
12) rated discharge pressure-7-10 $kg/cm^2$
13) Free air delivery at rated pressure-30-80
14) Discharge air purity with respect of solid particle-class 3
15) Discharge air purity in respect to humidity and liquid water-class 3
16) Discharge air purity with respect to total oil -class 3
17) conformity to standard ISO: 1217-latest
18) Compressor ISI Marked to IS:5456-latest-yes
19) air receiver supplied with compressor- yes
20) variable speed range-40-100%
21) capacity of air receiver- 300-500ltr
22) working pressure range 7-10bar
23) type of inner cooler/after cooler Finned/tube type/ other alternatives
24) design of tube/plate of inter cooler/ after cooler Finned or other alternatives
25) motor (KW/HP) 15/20
26) material of fin - aluminium
27) Instruction and safety devices - safety vale on air/oil separator vessel, discharge pressure gauge, lubricating oil pressure gauge, discharge pressure gauge, clogging indicator for air suction filter, power on off light indicator, mains circuit breaker, safety valve on air receiver.
28) minimum operating temperature- 0 degree celsius
29) maximum operating temperature - 60 degree celsius
30) operating relative humidity 80
31) Maximum altitude without derating correction - 3000mtr

## Purchase details
Date of publishing-18/09/2020
clarification start date - 18/09/2020
clarification end date -29/09/2020
Bid submission start date - 18/09/2020
Last date of submitting EMD and others document at iit kanpur - 30/09/2020
Sate of opening of technical bid - 30/09/2020

## Commissioning ( 26 May 2022)

## Compressor operation

### System operation
The Air Intake Valve provided is normally closed type. As the supply to the motor is on due to the vacuum created in the compressor, air enters in the bare compressor from suction filter. The compressed air is delivered to Air/oil separator. The pressure in Air/Oil separator starts rising. This air pressure signal passes through the Solenoid Valve and is given to the Air Intake Valve. This closes the air intake valve and supply of air to the compressor is cut off. Thus compressor is immediately unloaded. This ensures that the starting torque required is less thereby limiting the starting current of the motor. Also the motor is started in star connection. After a set time, the starter connects the motor in delta connection and compressor runs smoothly in unloaded condition. After a set delay time, the Solenoid Valve is energized and the signal line to air intake valve is cut off and connected to exhaust. With this the Air Intake Valve is immediately opened and compressor comes on load. It takes few seconds for the compressor to come on load depending on the motor rating. The moment the pressure rises in the Air Oil Separator tank, the oil flow to compressor is started, irrespective of whether the compressor is in loaded or unloaded condition.
Air/oil separator separates the oil from air/oil mixture down to 1 to 3 PPM by mechanical as well as with the help of air-oil separator element as described earlier. The minimum pressure valve starts opening at a pressure of 3.5 kg/cm² (full open at 4.0 kg/cm³). The compressed air from receiver then passes through the after-cooler part of the combi-cooler where it is cooled with air of fan driven by motor. An efficient moisture separator then separates the condensed moisture in the compressed & cooled air. The separated moisture is drained by mechanical auto-drain valve of the Moisture Separator. Pressurized air is now available at the air delivery valve for user's network.
When the demand for air decreases or when there is no demand, pressure builds up in the system. The pressure transmitter fitted after the Moisture Separator senses this pressure. When the pressure in the system increases beyond a set value, an electric signal is given to the Solenoid Valve and it is de-energized. The pressure signal line from receiver is connected to the Air Intake Valve and the compressor is immediately unloaded. At the same time the pressure signal from receiver through the Solenoid Valve is also given to Blow down Valve. The pressure signal opens it & receiver is connected to the suction side of the compressor. BDV has in-built spring resistance which helps to maintain a minimum pressure of 2.0 kg/cm'g during unloading. This not only ensures that the power consumption during No-load running is minimum, but also sufficient oil flow is maintained during No-load runnning.
Whenever the compressor is stopped, the Solenoid Valve de-energizes, Air Intake Valve closes, which ensures that there is no oil back flow from compressor to air filter. BDV gets opened due to pressure signal from Solenoid Valve. The air receiver gets connected to the atmospheric pressure through BDV to just after the Air suction filter and pressure in the receiver is relived totally. This ensures that when the compressor is started again, there is no pressure in the receiver.
The heat of compression is absorbed by oil besides sealing the rotor gaps and lubricating the moving parts including bearings. The oil collected at the bottom of the Air-oil separator tank is pumped to oil cooler using the air pressure in the tank. The oil is cooled by atmospheric air pumped by the axial flow fan and motor assembly fitted at the bottom of the cooler assembly with fan cowl Further, the cooled oil is filtered in oil filter and supplied to compressor.

If the oil is overcooled, the moisture in the air condenses and condensed water mixes with the oil. This affects the performance and life of oil. Compressor performance and life also gets affected. To avoid this overcooling, a thermal switch is provided in the oil line after the oil cooler. This switch switches off the cooling fan if the oil temperature falls below a set value

## Maintenance routine
### Daily
1) General unit cleaning
2) Drain condensed water from AOS before start
3) Check fluid level
4) Drain Condensed water from moister separator

### 1000 hrs
1) Clean air filter element
2) blow out combi cooler
3) change oil filter element
4) check and tighten all electrical connection
5) check condition of contacts on contactors
6) change K smart fuel

### 2000 hrs
1) Blow out combi cooler
2) change air filter element
3) check condition of contacts of contactor
4) check and tighten all electrical connection
### 4000 hrs
1) change K smart fuel
2) change oil filter element
3) change air filter element
4) change air oil separator element
5) check operating conditions of accessories replace wear parts
6) check and tighten all electrical connection
7) blow out combi cooler
8) check condition of contacts on contactors
### 8000 hrs
1) change K smart fuel
2) change oil filter element
3) change air filter element
4) change air oil separator element
5) change service Kit for MPVL
6) change service kit for thermostatic valve
7) change service kit of moisture separator
8) change gasket kit, o ring kit
9) check operating conditions of accessories, replace wear parts
10) check and tighten all electrical connection
11) Blow out combi cooler
12) check condition of contacts on contactors
## Other important details

### Safety

The compressors designed and manufactured by KPCL are for safe operation at the stipulated conditions. The safe operation of the compressor lies with the personnel operating and maintaining it. Hence, those who are trained and clearly understand this OPERATION AND MAINTENANCE MANUAL only shall operate the compressor.
Never start the compressor when it is not safe to do so. Never operate the compressor with known unsafe conditions. When the compressor is unsafe, tag the unit to indicate to other and disconnect the power supply either by removing the fuses or removing the power wire connections to avoid accidents
This air compressor is not explosion proof and hence has to be installed away from the explosion area. Do not use the air from this compressor for direct contact with food and medicinal substances and do not use for breathing purpose. Do not modify the compressor without getting the written permission from KPCL
Pressure release: The compressor is provided with pressure relief valve to release the pressure from the air-oil separator tank incase the pressure exceeds the set values and electrical interlocks fail. Do not open the valves / air lines / air-oil separator tank connections or plugs without releasing the pressure by using the pressure relief valve (safety valve).
Fire or Explosion: Install fire extinguishers near the compressor. Do not store
inflammable materials near the compressor Keep the compressor clean from oil
spills to ensure safety to operating personnel and equipment.
Hot Surfaces: Do not handle/touch the hot surfaces on the compressor without using proper protection and handling devices. Avoid body contact with hot surfaces, oil and air.
Electrical safety: Ensure electrical safety standards are adhered for the safe operation of the compressor and personnel. Do not store materials inside the electrical panel even though free space is available. Attempt repairs after removing the fuses in the incoming power supply lines and keep notice near the fuse box to avoid accidental connections.
Waste disposal: Follow the local safety standards for disposing the used oil, filters and other used parts of the compressor to protect the environment
DANGER
Death or serious injury may result from inhaling compressed air without using proper.
safety equipment

### COMMISSIONING THE COMPRESSOR
- Switch ON the main power supply and confirm "Healthy LED is glowing on the microcontroller after displaying Date & Time & Welcome message.
- Press key on the microcontroller to confirm the display "PT-1 DIS AIR PR" is 00.0. This display to indicate the air pressure at compressor outlet.
- Press again to get the display "PT-2 BEF OIL PR with value 00.0 to confirm no pressure in the Air oil separator tank.
- Remove the canopy door below the electrical panel to view the motor.
- Press Start button (green color) on the microcontroller to make the main motor ON. If motor is energized, switch off the compressor by pressing Off button (red color) on microcontroller. Check and confirm the direction of the rotation is in line with the direction arrow mark sticker pasted on the fan cover If the direction of rotation is wrong, check the main power supply lines and correct them. If the direction of rotation is correct, fit the canopy cover in position.
- Close the ball valve at the compressor air outlet line.
- Switch ON the compressor and confirm, "Comp. ON LED is ON Now the compressor will get loaded with "Load" LED in ON condition,
- Run the compressor for ONE minute and switch OFF to make the oil in the oil lines to flow back to the tank.
- Check and ensure the display for PT-2 is 00.0 when the compressor is in OFF condition. This is to ensure there is no pressurized air in air-oil separator tank when compressor is in OFF condition after Blow-off valve releases the air from tank,
- Check the oil level on the sight glass after 5 mins Add oil till the level reaches to middle level of the sight glass.
- Ensure the threaded plug provided on oil pour point is tightened fully.
- The compressor will go to "Unload" mode once the pressure reaches maximum pressure / unload pressure. This is when PT-1 DIS AIR PR display is unloading pressure value of the model. When the compressor is in Unload mode, the "Load" LED will go OFF.
- Open the canopy panels and confirm no air and oil leakages during this run at the joints/fittings.
- Open the ball valve slowly till the pressure PT-1 value on microcontroller display is the working pressure of the model.
- Ensure that Fan motor is ON continuously while running the compressor.
- Run the compressor and record the values from the microcontroller display by pressing button.
- Refer the specifications given in Section 5 of this Manual for each model to confirm the compressor performance is within the limits
- Ensure the temperature inside the compressor room is not more than 5°C above the temperature outside the room during the continuous run.
- Refer Troubleshooting guide given in this manual for any abnormalities found Report to KPCL, if problem persists after applying remedial actions given in the trouble-shooting guide.

## After commissioning
FSR No.- MKT/CUS/P/SRV/305992

Date of commissioning 26/05/2022
Oil makes and grade K Smart

Service engineer- Krishna Yadav

#### Voltage and ampere on loading condition

RY-415
YB-413
BR-414

Ampere
R-24
Y-26
B-25

#### Loading and unloading pressure - 8 bar and 7.5 bar, Temperature on running conditions 85 degree celsius.
#### Compressor deliver constant flow rate 290 Kg/hr @ 2 bar cylinder pressure

### cfm calculation

- Time taken to fill 0.5$m^3$ from ambient pressure to 8 bar is 1.54 min, all the calculation they have done on psi their calculated cfm is 88.65 $ft^3$,
- The pressure was maintained 2 bar for fully open valve, Temperature, 85 degree celsius, Relative humidity was 38%, Dew point temperature 62.36 degree celsius, air density was 1.86373 kg/m^3, volume flow rate 80 cfm, which is equal to 2.2653 m^3/ min. mass flow rate calculated 253 kg/hr and rotameter reading was around 250-290 kg/hr.
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