Pressure Switch ek aisa device hota hai jo kisi specific pressure value par electrical contact ON ya OFF karta hai. Iska use mainly safety systems, alarms, pump control aur pressure cut-off ke liye hota hai.Jaise hi pressure ek defined limit pe pahuchta hai, pressure switch uss moment par relay ya contact ko open ya close kar deta hai.
Kahan Use Hota Hai?
- Boiler me overpressure protection
- Compressor auto-cutoff
- Water tank me level detection
- Hydraulic ya pneumatic system me interlock
NOTE: Har pressure switch ke do main parts hote hain:
- Mechanical Sensing Element (diaphragm, bourdon, etc.)
- Electrical Contact (NO/NC – relay type)
Pressure Switch Kaam Kaise Karta Hai?
Working Principle:
- Pressure switch ke andar ek diaphragm/spring mechanism hota hai.
- Jab pressure increase hota hai, diaphragm compress hota hai aur spring ke against kaam karta hai.
- Jab pressure set point tak pahuchta hai, ek electrical contact (SPDT) trigger hota hai – ya to NO → NC ho jaata hai ya vice versa.
Pressure Switch Set Karne Ke Tools & Safety
Zaroori Tools:
| Tool | Use |
| Hand Pump / Calibrator | Desired pressure apply karne ke liye |
| Multimeter | Contact open/close dekhne ke liye |
| Screwdriver | Set point adjust karne ke liye |
| Teflon Tape / Wrench | Leak-proof connection ke liye |
Safety Precautions:
Pressure source ko control karke use karein
Electrical connection dekhte waqt gloves aur insulation ka use karein
Sensor ko over-pressure se bachaayein
Field Mein Step-by-Step Setting Procedure
Step-by-Step Process:
| Step | Description |
| Isolate Pressure Source | Line pressure band kar dein ya hand pump use karein |
| Pressure Apply Karein | Calibrator se pressure gradually badhayein |
| Set Screw Locate Karein | Switch ke upar ya side me set screw hota hai |
| Set Point Adjust Karein | Screw ko clockwise ya anticlockwise ghoomaayein jab tak contact desired pressure pe toggle na kare |
| Multimeter Se Confirm Karein | Contact open ya close hone ka pressure dekhkar confirm karein |
| Reset Pressure | Pressure hataakar switch ka normal position check karein |
Agar switch me deadband ya differential adjustment bhi ho, to use bhi manually set kar sakte hain (some switches like Danfoss, Switzer, etc.).
Multimeter Se Contact Kaise Check Karein?
Multimeter ko continuity mode pe rakhein
Switch ke terminals (NO/NC) pe probe lagayein
Jab desired pressure apply hota hai, to multimeter beep karega ya reading change hogi
Isse aapko pata chalega ki contact kis pressure pe toggle ho raha hai
Example for Easy Understanding
Maan lijiye ek pump ke liye aapko pressure switch ka high pressure cut-off 5 bar pe set karna hai.
- Aap calibrator se pressure badhate hain
- Jab pressure 5 bar pe pahuchta hai, multimeter pe contact NO se NC shift hota hai
- Agar ye 4.5 bar pe hi ho gaya, to set screw thoda adjust karte hain
- Phir se 5 bar pe set hone tak repeat karte hain
Quick Interview Answer
Calibrator ya hand pump se pressure gradually apply karte hain, phir set screw adjust karte hain taaki switch desired pressure pe toggle kare. Multimeter se contact (NO/NC) ka status dekh kar confirm karte hain.
Conclusion
Pressure switch ek simple but critical device hai jo system ki safety aur automation ke liye kaafi important hota hai. Iska proper setting ensure karta hai ki switch exact pressure pe operate kare – na jaldi, na der se.
Instrumentation Use Cases:
- Boiler trip system me high-pressure switch
- Water pump auto-off low-pressure switch
- Oil & gas plant me safety interlocks
- Hydraulic press me pressure cut-off logic
Common Mistakes to Avoid:
| Mistake | Impact |
| Set screw over-tightening | Calibration disturb ho jaata hai |
| Without pressure calibrator setting | Approximate setting hoti hai, reliable nahi |
| Electrical contact bina multimeter check kiye | Galat triggering ho sakta hai |
| Over-pressure apply karna | Switch diaphragm damage ho sakta hai |