Valve Sizing
The chart below allows you to size a valve to give a specific pressure drop against a given flow rate of water. However, for air, steam, gases or other liquids you should consult our Sales Office for the sizing of NAF-Check non return valves.

Northvale has invested in computer aided design facilities and to this extent we can size valves for your applications and give accurate predictions of pressure drops etc. as such we require the following information:

Oversize Valves
Oversized valves should not be used as this causes the disc to flutter and will quickly wear out the spindle bearings.

The lines a to d on the graph below represent the point at which the valve attains its fully open position and therefore its correct sizing for its relative installation orientation.

a. Horizontal line with spring
b. Vertical line with spring
c. Horizontal line without spring
d. Vertical line without spring

Leakage Rate
The NAF-Check non return valve, when supplied, has an intended maximum leakage rate through the body/disc seating area of 1 cm3 per minute irrespective of valve size. This meets the requirements laid down for this test under API 598 and ANSI B16.34/MSS SP-61.

Conversions
1 m water guage	3.28	feet water guage
	1.42	psi
	0.098	bar
1 m3/hr water	0.28	litres/sec
	3.66	igpm
	0.59	ft3/min

Introduction
Installation & Maintenance
PN 25-40-100 Class
ANSI 150-300
Limitations
Certification