Square edge orice plate installation

If it's a bypass orifice flowmeter, it will simply not indicate if the flow is backwards relative to the orifice, as the indicator relies upon forward flow in order to lift the bob to a point where the flowrate can be read.

Regardless of whether it is a bypass type, why install it backwards? The shape of the orifice has been selected by the manufacturer so as to give the closest accord between the design intent and the installed performance. To install it otherwise would be simply pointless!

It's only important when the thickness of the orifice at the bore is less than the thickness of the plate. The downstream side will have a bevel or a counter bore, which would not be a square edge which would cause errors in the differential pressure readings if installed backwards. For cases when the orifice thickness is the same as the plate thickness, the manufacturer may have only machined the unstream side to a square edge, and not worried about the down stream side.

YES , the orifice plate has to be installed in tHE direction of FLOW as inidcated on teh orifice plate

Is there any marking such as the bore size at 20C, this marking normally faces upstream. If it only has one square edge,assuming that it is new,then the square edge faces upstream.

"here does the orientation(direction) is imporatnt to this type?"

It depends if you want it to work or not!

The larger question is why you would even consider installing it backwards.

Perhaps you should try farming.

I would guess that the question is being made after the fact. It was installed backwards and somebody realized after the line started back up. Now they are wondering whether that number is accurate or not. Like everyone else says, no it is not. Make sure that the sharp edge is the leading edge of the plate. Look in Perry's or Crane for a diagram, they give a good graphical representation of what it should look like. A lot of plates, like you say, will have the information stamped on the leading edge of the plate. Typically, I get at least the tag number and orifice diameter stamped on the handle. Therefore, when looking downstream, you should read the text on the orifice handle.

Hi,

Just question:

can we use Squre edge orifice plate to measure as export & import gas flow with same orifce?

yes,but you need an orifice plate with 2 square edges!

are you using an orifice carrier ring or d and d/2 tappings - your calculations for dp will be different for each direction.

how accurate do you want to be? why not use a thermal mass meter (usual for gases) or turbine meter (most expensive but same output for either direction i.e.20/0/-20mA or whatever)