Joined: June 15, 2008
Posts: 5
Location: India
Status: Offline
Posted:
July 27, 2008 - 02:31 AM
Post subject: how to Calculate square root extractor
A DP transmitter having range of 0-15000 mmh20 , its for flow TX and shows value with square root extractor --should be calibrated for 25%,50%,75%
what pressure should be the input, to get the exact square root value.
i know that sqaure root of Dp is flow ,
but iam not clear in calucation,
when i applied and checked the list is as below,
25%-937.5
50%--3750
75%--8437.5
it would be helpful if any one clear me with correct mathemetical explanation how we had obtained this value --
fauzi.edward
ICE Newbee
Joined: Feb 21, 2010
Posts: 1
Location: Indonesia
Status: Offline
Posted:
Feb 23, 2010 - 11:21 AM
Hi Arif...
here is,
for detail Square root extractor my simple formula,
peace,
fauzi
paulzaki
ICE Newbee
Joined: July 27, 2010
Posts: 1
Status: Offline
Posted:
July 27, 2010 - 08:36 PM
Fauzi, Thanks for your reply.
However, could you please explain the derivation of 0, 6.25,25,56.25 and 100 % (square root).
THanks in advance.
Zaki
Carl_E
ICE Student
Joined: May 30, 2010
Posts: 11
Location: Illinois, USA
Status: Offline
Posted:
July 28, 2010 - 11:29 PM
Part of the problem in deriving or understanding the square root calculation is that it is commonly stated that "flow rate is the square root of the DP". That's a simplification. The square root is calculated on the percentage of flow rate as illustrated in the table below.
Primary DP flow elements are ALWAYS sized for a maximum flow rate at a given DP. So, and 100% flow rate is always a known for DP applications.
It isn't clear from the wording in original post whether the calibration is to percentage of flow or percentage of DP. But the values for percentages given are for DP in mm H2O. One would expect that years ago, but today?
In an era of pneumatics, the flow rate values were only known by what was printed on the chart recorder. Indicators were always in percentage of flow rate because that's how the square root was extracted, from a follower on a square root cam where the cam rotated proportional to DP.
But with today's pervasive electronics, one would assume that the flow rate would be available in flow engineering units, as a direct readout.
At any rate, you can see the relationship between DP, square root and percentage of DP on the table.
Latest Posts
Forum FAQ
Usergroups
Preferences
Watched Topics
Watched Forums
