# Homework Help: Industrial current to pneumatic convertor

1. Aug 23, 2011

### zulfiqar

1. The problem statement, all variables and given/known data
A Current to pneumatic convertor which is shown here in the attachment has the given data which is
Kc=2500N/A (constant of proportionality
X+Y = 100mm
Z=75mm
A=5cm^2

1-to check the response of I/P as per graph waht is the suitable value of x and y
2- what is the value of Fs

2. Relevant equations

Pout = (Kc*Y/A*X)Iin+Fs*Z/A*X

3. The attempt at a solution
Given data is
Kc =2500NA-1 or 2500,000mNA-1

X+Y = 100mm

Z=75mm

A= 5cm^2 or 500mm^2

Solution
The balance equation of the system is

Pout = (Kc * Y/A*X)Iin + Fs*Z/A*X

Y=MX+C

Now by looking the graph the intercept c of the line run through zero so
The Fs*z/A*X part of the equation iS neglected so new equation is lik
Pout = (Kc*Y/A*X) Iin

Or Y = MX

As per the graph the value of
Pout =1 bar or 100,000pascals
Iin = 20mA
now by putting these values in the above equation
100,000 = ( Kc*y/A*X) 20

Kc*Y/A*X = 5000

Now by putting the value of Kc and A

2500,000*Y/500*X = 5000

SO
Y/X = 1
Now as per the given data the

X+Y = 100
And Y = 100-X

Now by putting this value of X in the above equation

100-X/X = 1
100-X =1X
100 =1X+X
100 =2X
X =50mm

Now by putting this value of X in the given x+y =100 we will get the value

X+y = 100

50+Y = 100

Y = 100-50

Y = 50mm

so the value of x = 50mm and Y= 50mm
I am not sure this the correct solution and the unit selection is correct or not

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2. Aug 24, 2011

### Staff: Mentor

Your values for x and y look okay to me.