General
The tilting disc check valve NAF-Check is designed for installation between two pipe flanges in horizontal pipelines with upward flow.

Installation
To obtain optimum function of the NAF-Check and of the circuit in which it is installed, the following instructions should be carefully followed. Consult if in doubt as to the location or function of NAF-Check.

Clamp the valve between the two pipe flanges using through-bolts. NAF-Check is available for all common international flange standards: see catalogue sheet below.

A flow-direction arrow is cast into the valve body-lifting eye. Make certain that the medium's flow coincides with this arrow.

Centre the valve carefully between the pipe flanges so that the disc can move freely (Fig 1) and is not obstructed by the edge of the pipe flange during operation (Fig 2).

Flange gaskets
NAF-Check has plane gasket faces. We recommend the following gasket widths for pressure class PN 25 (ANSI 150).

PN40/100 (ANSI 300) valve's sealing surfaces are dimensioned for standard gaskets.

Centering
Insert the two bottom through-bolts in the pipe flanges and cradle the valve on these two bolts. Use correctly dimensioned shims to centre the valve. The centring operation may be aided by easing the valve into place with help of wedges hammered between the valve body and the through-bolts.

Make certain that the disc's stub shafts are perfectly horizontal in the horizontal lines. The valve is correctly positioned when the lifting eye on top of the valve body is vertical.

Valves installed in vertical lines must, of course, also be accurately centred. In all conventional applications, the valve must open upwards.

Maintenance
NAF-Check will normally not require any service work. The valve is available with an auxiliary spring to accelerate closing, or without a spring assembly. The springed version is recommended for fluid media. A springless version may easily be equipped with a spring to obtain extra rapid closing.

Valve Flange Index


Introduction
PN 25-40-100 Class
ANSI 150-300
Limitations
Certification
Sizing & Pressure Drop