Some MEK(General) Question and Answer

1.      How does a Bourdon pressure gauge work'?
Elliptical pressure transducer, bourdon tube, open @ one end to pressure liquid. Other end closed, connected to a sector and pinion connected to the pointer which moves on a calibrated scale. Due to applied pressure the bourdon tube tends to become circular, which moves the free end and thus moves the pointer.

2.      How do you read the lubricating oil pressure of fridge compressors?
Pressure gauge reading – suction pressure = L O pressure.

3.      Sometimes the pressure gauges used in fridge systems also have temperature readings. What is the use of this?

a.       Compound pressure gauge gives pressure and corresponding saturation temperature.

4.      What is mean effective pressure of diesel engine?
Theoretical const pressure which can be assumed to be acting on the piston during the power stroke. Area of indicator diagram/length of dia.

5.      What the cooling water treatment?
Non nitrite. Nitrite borate.

6.      What is a lantern ring?
Perforated hollow ring situated @ centre of stuffing box or gland packing. Cooling sealing and lubrication.

7.      If a bursting disk ruptures, what will be your action?
Stop Compressor immediately. Trouble shoot n overhaul.

8.      If the inter-stage relief valve is lifting,what could be the reason?
Intercooler tube leakage, HP suction valve leaking

9.      Why is deck seal used in IG systems?

a.       Prevent back flow of hydrocarbon gases into the engine room.

10.  What is the allowed C02 content in IG?
How is it controlled? Max 8%, Alarm @ 5%.Controlling air fuel ratio of the boiler.

11.  Safety devices in setting tanks
flame trap on vent, weighted cock on sounding pipe, overflow line with sight glass, high and low level alarms, spring loaded drain valves,Quick Closing Valve on Pump Suction.

12.  What is back pressure valve and where is it used?
Slow and controlled cooling by increasing pressure and reducing rate of evaporation.

13.  In a centrifugal pump, why wi1l starting torque he less when starting with discharge valve shut?
Discharge of pump is minimum, discharge head maximum, power consumed minimum, thus torque minimum.

14.  What is a Dead mans alarm?
Fitted in E/R must be acknowledged every 15 minutes, must be activated when entering ER during ums condition. If not acknowledged would give an alarm on bridge.

15.  What is VRF?
Variable refrigerant flow

16.  How does a Quick closing valve work?
Air pressure acting on a servopiston mounted on the spindle
keeps the valve open against spring force. When air supply cut off, spring force causes valve to shut.

17.  What is the functions of the friction clutch mechanism used in purifiers?
Reduce starting current of purifier motor.

18.  How does a Salinometer function?
Measuring flow of current through a known quantity of water.