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| Current topic: Pressure Measurement |
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| Current Question: |
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Selection of the transmitters |
we r going to bid for a transmitter tender,and now selected the models of FUJI,but there is one doubt about the selection. The customer asked for one DP transmitter of (range 0-2.71KPa,maximum S.P. 16MPa), right now we chosen FKC 22(span 0.1-6KPa,MSP. 10MPa),but the MSP. cann't match the required MSP.16MPa.
So we want to know wheahter we can use FKC 33(span 0.32-32KPa),the MSP is 16MPa, can satisfy the MSP. requirement of customer.
According to the specification of FKC transmitter,if we adopt FKC 33 for the use of 0-2.71 range, the accuracy would be influenced.
but how many would the accuracy be influenced? The original accuracy is 0.065%(the precondition is the selected span should exceed 1/10 of maximun span,otherwise the accuracy would be degraded).
based on the formula in the specification, I have counted the accuracy of FKC 33 which is used for 0-2.71KPa range, it would be 0.075%. Does it mean the accuracy is 0.075% of 2.71KPa? or 0.075%of 32KPa?
and I have some doubts on the following items.
1). how many is 1/10 of URL for Model "FKC 33"?
3.2KPa? or 0.32+(3.2-0.32)/10?
2)how to understand "Remark: To minimize environmental influence, span should be greater
than 1/40 of the max. span in most applications."
Does it mean we can use the transmitter which span is greater than 1/40? We know the accuracy would be influenced,if the selected span is between 1/40-1/10 of URL.
Your prompt help would be very appreciated. thanks. |
| Posted: Sat Sep 26th, 2009 7:04 p.m. |
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One Reply |
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Selection of the transmitter accuracy |
Firstly, you are correct to select the FKC33 as the way to meet your MSP requiement of 16MPa.
With regard to the span. This transmitter can be calibrated at a minimum span of 0-0.32kpa, which is a turndown ratio of 100:1.
As you corectly observed, the smaller the span, the greater the environmental effects. Hence our suggestion that the transmitter is used at turndown of less than 40:1 (in this case 0-0.8Kpa).
Your calculation for the effect on accuracy is correct. But to clarify the effect is 0.075% of the calibrated span , which in your case is 2.71Kpa.
Please note that the above calculation is the guaranteed performace for this tranmitter.
Our recent experience of these transmitters suggest that most tramsitters leave the factory with an accuracy of better than 0.005%. The data sheet is therfore very careful in its documented claims.
If your need further details, please don't hesitate to ask.
Malvern |
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| Mon Sep 28th, 2009 11:39 a.m. |
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