What is an Orifice Plate?

Orifice plates are often used where a pump delivers higher pressure than is required by a system meaning an orifice plate is added to the discharge line to generate backpressure ensuring the pump operates on curve. 

They can also be used for reducing flow.

Sometimes orifice plates are used where to achieve a particular duty point a pump delivers more pressure than is required by the system. 

They are also used when one pump is used to achieve two duties and an orifice plate is inserted in one discharge line

To size an orifice plate is a little complicated but is typically calculated according to the following calculation: 

SNT125-100-200/30KW/2900 RPM

1ST DUTY - 2,700 DM³/MIN @ 2.0 BAR - (162M³/HR @ 20.4M)

2ND DUTY - 1,100 DM³/MIN@ 4.7 BAR - (66M3/HR@ 48M)

196MM IMPELLER

Q1 = 66M3/HR
Q2= 162M3/HR
H1= 4.25M
H2=25.5M

(Q2 / Q1) ² = H2 / H1

Orifice plate sizing for Q1 & H1 = Diameter (66 x 133.3) / 4.25 = 65mm

Orifice plate sizing for Q2 & H2 = Diameter (162 x 133.3) / 25.5 = 65mm

Orifice Plates

To calculate the diameter of the hole in the plate:

WHERE D =Diameter of the hole in mm
H= Head Loss required in Metres
Q= Flow in M³H

D = Q x 133.3 / H

Alternatively, we can provide pumps complete with orifice plates to deliver the duty you require, pumps which can deliver two duties simultaneously or a range of duties when driven by VFD.

Contact us for more information on how.