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manufacturer of industrial valves

Check valves KM – General information


Description and design

Vertical lift-type check valves KM are characterized by high reliability and long service life issuing from a simple and elegant structural design and high quality of wrought semi-products used.

The main parts of the one-piece shell are: body containing a seat assembly which is usually weld-deposited with a high-quality alloy overlay and equipped with connecting ends for connection to the piping, disc made of high-quality alloyed steel or having a seat which is weld-deposited with a high-quality alloy overlay, disc guides and bearings. In addition to the above, the split design of the shell contains a body connector with connecting end, gasket and bolting components. Additional components of the check valve with automatic relief are spring, piston, piston bushing, orifice plate insert made of hard stainless steel, and orifice plate made of hard metal.

Vertical lift-type check valves are designed in compliance with ČSN EN, ČSN and DIN standards.

Common design features of all types of vertical lift-type check valves

Vertical lift-type check valves are not designed as conventional isolating valves, but their function is protection of pumps against reverse flow of the pumped fluid. Vertical lift-type check valves are uni-directional valves only. Their operation is fully automatic.

The valves can be equipped with following connecting ends: flanges according to ČSN EN, ČSN or DIN standards, flanges with adapted raised faces (recess, groove) butt-welding ends.

A one-piece shell is preferred for check valves with flanged ends. Check valves with welding ends have always a two-piece design of the shell (body-cover).

Material specification

Vertical lift-type check valves are manufactured with bodies made of the following main materials:

990X.0

990X.3

990X.4

Depending on service conditions, other body materials may be used by agreement as well.

Applications of vertical lift-type check valves

Characteristic of the valve function and classification of the service fluid

Vertical lift-type check valves described in this catalogue are designed to protect pumps against reverse flow of the pumped fluid. However, they are not designed as conventional isolating valves.

Check valves of types KM 9901 and KM 9902 are designed to be used with fluids in groups 1and 2 according to Section 3(1)(a, b) of Decree of the Government No. 26/2003 as subsequently amended, i.e. water with the exception of potable water, non-aggressive fluids (liquids, gases, vapours, air), oil and oil products, gaseous fuels, inorganic and organic media (acc. to materials used and after an agreement with a manufacturer). This specification corresponds to Article 9 (2.1, 2.2) of the European Parliament and Council Directive 97/23/EC. The service fluid shall not contain hard and abrasive particles as this could damage the seating surfaces and bring about heavier untightness or sticking of the disc or seizing of the piston in the bearings. The same applies to impurities in the piping system during installations, repairs or replacements.

Check valves of type KM 9903 are designed to be used with fluids in group 2 according to Section 3 (1)(b) of Decree of the Government No. 26/2003 as subsequently amended, i.e. water with the exception of potable water, non-aggressive liquids. This specification corresponds to Article 9 (2.2) of the European Parliament and Council Directive 97/23/EC, but it is recommended to use this valve for demineralized water only. The service liquid shall not contain hard and abrasive particles as this could damage the seating surfaces and bring about heavier untightness or sticking of the disc or seizing of the piston in the bearings. The same applies to impurities in the piping system during installations, repairs or replacements.

Temperature and pressure of the service fluid with respect to the valve body material

The limiting values of service pressure and temperature of the fluid with respect to the material grade from which the valve body and/or cover are made are shown in the following system of pressure/ temperature ratings. Because the split design of the valve incorporates a gasket made of expanded graphite or a combined gasket or a purely steel gasket suitable for high temperatures (recommended up to +550°C) to seal the body-cover joint, the strength of the valve body material is the main factor for determination of limiting conditions that define the area of safe use of the check valve.

Type number composition

KM 990A.B CDEF – GHHH, where:

A – symbol for valve type
   1 – lift-type check valve
   2 – lift-type check valve with branch piece
   3 – lift-type check valve with automatic relief
B – symbol for shell design
   1 – one-piece body
   2 – all-welded body
   3 – two-piece shell consisting of body and cover
C – symbol for flow pattern
   1 – straight
D – symbol for connection to the piping
   1 – flanged ends
   2 – welding ends
E – symbol for operation
   7 – automatic
F – symbol of spring over plug (mention ‚P‘, only for variation with spring)
G – symbol for material of body and body connector
   0 – wrought stainless steel
   3 – wrought alloyed steel
   4 – wrought carbon steel
HHH – symbol for PN (16, 25, 40, …, 400)

Quality and certification

The company has been applying a quality management system according to EN ISO 9001 since 2004, which is being regularly tested, thus demonstrating the ability to meet customer requirements and achieve high quality products and services.

Vertical lift-type check valves are in compliance with the Pressure Equipment Directive 97/23/EC (Decree of the Government No. 26/2003), have been certified by Strojírenský zkušební ústav (Engineering Testing Institute) in Brno, and can bear the CE marking.

Inspection and testing

All vertical lift-type check valves are subject to tests according to EN 12 266–1 as a standard, i.e. shell strength test P10, P11, seat tightness test P12 (water pressure 1,1×PN and air pressure 0,6 MPa), leakage rate A – zero leakage, operability test F20. Standard ČSN EN 13709 specifies that a seat leakage corresponding to leakage rate C according to ČSN EN 12266–1 is allowed in case of test P12.

If required by the Customer, additional tests may be performed as well.

Documentation

The following documentation is delivered together with the check valve as a standard:

Additional documents as required by the customer (i.e. certificate according to EN 10 204 3.1 or 3.2).

Spare parts

Spare parts can be supplied according to an agreement with the customer.

Guarantee

Standard guarantee period is 24 months from receipt of goods.

Installation, service and maintenance

Vertical lift-type check valve shall be installed in vertical position. As it is a uni-directional valve, the fluid flow shall correspond to the arrow marked on the valve body. If the values of temperature and pressure of the fluid and quantity of the fluid flowing through the branch piece as specified on the valve label are adhered to, the check valve operation is fully automatic. More detailed instructions for use of the check valves are given in a document titled Installation and operation instructions which is enclosed to each valve shipment.

Ordering

The following data shall be specified in the purchase order:

Ball valves|Three-way valves|

Check valves|Services


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