# Mechanical Engineering - Compressors, Gas Dynamics and Gas Turbines - Discussion

### Discussion :: Compressors, Gas Dynamics and Gas Turbines - Section 1 (Q.No.1)

1.

In a four stage compressor, if the pressure at the first and third stage are 1 bar and 16 bar, then the delivery pressure at the fourth stage will be

 [A]. 1 bar [B]. 16 bar [C]. 64 bar [D]. 256 bar

Explanation:

No answer description available for this question.

 Hardik Patel said: (Jul 15, 2013) In multistage compressor the pressure in each stage follows geometric progression: For 2nd stage: SQRT (1*16) = 4. For fourth stage: 4*4*4 = 64.

 Nanu Dayma said: (Nov 5, 2013) Four stage compressor 3rd stage me intercooler hota so its temperature and pressure is constant 4 stage compressed so increased delivery pressure.

 Abhishek Chavan said: (Nov 20, 2013) How to came 64 please explain the example?

 Guna said: (Feb 15, 2014) How to came 64?

 Karthik said: (Mar 29, 2014) How does it came 64?

 Kanhai said: (Apr 24, 2014) We know in multistage compressor: P2/P1 = P3/P2 = P4/P3. Since, P3 = 16. P1 = 1. So from, P2/P1 = P3/p2. Hence, P2 = 4. Now P3/P2 = P4/P3. P4 = 64.

 Francies said: (Aug 7, 2014) We know that p2 = (p1p3)^(1/2). Therefore p2 = (1*16)^(1/2), p2 = 4 bar. Therefore P4/p2=p3/p1, P4 = 64 bar.

 Deepak Kumar said: (Nov 11, 2014) When we know that for multistage compressor p2/p1 = p3/p2 = p4/p3. Since p3 = 16, p1 = 1 so p2/p1 = p3/p2 then p2 = 4 also p3/p2 = p4/p3. 16/4 = p4/16. p4 = 64.

 Rajeev Raj Singh said: (Dec 2, 2015) Since pressure ratio is constant for a compressor. So firstly found pressure ratio. And then make dual like p2/p1=p3/p2=p4/p3 and solve this.

 Bipin said: (Jun 20, 2016) The answer can get by following this one P2/P1 = P3/P2 = P4/P3.

 Anj said: (Apr 25, 2017) Fourth stage means P5/P4 = 4*4*4*4 = 256.

 Narasimha said: (Jul 22, 2017) For multi satge compressor p2/p1=p3/p2=p4/p3, p2/p1=p3/p2 from here we get p2=4 then by this relation p4/p3=p3/p2, p4=64.

 Parseltounge said: (Aug 3, 2017) It follows a geometric pattern.

 Mohit Kumar said: (Oct 23, 2017) Good explanation @Natasha.

 Amit Ankush Vidarbh said: (Mar 22, 2018) The delivery of forth stage=p5. p5=256.

 Pradeep said: (Nov 6, 2018) And P5=256.

 Rahul said: (Jun 10, 2019) Thanks all for explaining.

 Mayur Desai said: (Jul 7, 2019) There is clearly mentioned about four stage it means; (P2/P1)*(P3*P2)*(P4*P3)*(P5*P4)= 4*4*4*4=256. So, the right answer is D.

 Rohit said: (Sep 23, 2019) The delivery of forth stage = p5. p5 = 256.

 Suresh said: (Nov 16, 2019) The first two values given are delivery pressures at 1st and 3rd stage compressors, we have to find delivery pressure at 4th compressor. We have p3/p2 = p4/p3 = p5/p4. p2 = 1, p4 = 16, p5 = ? => p3 = (1*16)^(1%2),=> p3 = 4. Similarly p4 = (p3*p5)^(1%2) => p5 = 64.

 Savan Kumar said: (Jan 4, 2020) Thank you @Suresh.

 Vinod said: (Jan 11, 2020) Why 256 bar is wrong? Explain.

 Sekhar said: (Feb 20, 2020) The answer must be" D". Because delivery pressure at the fourth stage means we should find P5, not P4. So P5 = 4^4.

 Tarik said: (Apr 4, 2020) D is the answer.

 Bawa said: (Apr 10, 2020) Thanks @Suresh.