Check Valve Types
Batu Valve check valves (non-return valves) prevent a medium conveyed under pressure in a pipeline from flowing back when the line pressure drops. Opening depends on a rise in inlet pressure and closing on a drop in line pressure; no lever or actuator is required.
Check valves are manufactured in four designs according to the shape and movement of the closing element: swing, disc, spring-loaded ball and lift. The operation of each design, the lines on which it is used and its technical document are given below.
Batu Valve check valves
Design: Swing · disc · spring-loaded ball · lift
Connection: Flanged · threaded · wafer
Pressure: PN 16 – PN 40
Size: DN 15 – DN 300 · R ½" – R 4"
Body: Steel · cast iron · brass / sphero
Medium: Water, hot water, steam, compressed air
Product range
| Design | Type code | Body | Connection | Pressure | Size |
|---|---|---|---|---|---|
| Swing | BÇV-Ç | Cast iron | Flanged | PN 16 | DN 50 – DN 300 |
| Disc | BÇV-D | Brass / sphero | Wafer | PN 16 | DN 15 – DN 200 |
| Spring-loaded ball | BÇV-FL | Steel | Flanged | PN 16 / 40 | DN 15 – DN 200 |
| Spring-loaded ball | BÇV-Dİ | Steel | Threaded | PN 16 / 40 | R ½" – R 4" |
| Lift | BLÇV | Cast iron | Flanged | PN 16 | DN 15 – DN 200 |
Check valve designs
Swing check valve
BÇV-Ç · Cast iron · Flanged · PN 16 · DN 50 – DN 300
In a swing check valve a hinged disc opens with the flow and returns to its seat when the flow stops. Resistance to flow is low; pressure drop is therefore low and the design is widely used on horizontal lines.
When the flow stops suddenly the disc closes late. The swing design is therefore the most susceptible to water hammer.
The body, cover and disc are cast iron; the seat is brass and the disc seal EPDM. The wearing parts are the hinge pin and bush.
Swing check valve, cross-section
Disc check valve
BÇV-D · Brass / sphero · Wafer · PN 16 · DN 15 – DN 200
The disc check valve is a slim-bodied design clamped between two flanges.
It is compact and light, and is preferred where installation space is restricted. Being spring-loaded, it operates on both horizontal and vertical lines.
The body is brass or sphero; the disc is stainless steel or sphero, and the spring, retaining ring and ring are stainless steel.
Disc check valve, cross-section
Spring-loaded ball check valve
BÇV-FL · BÇV-Dİ · Steel · Flanged · threaded · PN 16 / 40 · DN 15 – DN 200 · R ½" – R 4"
The spring closes the ball the moment the flow stops; the risk of water hammer is therefore markedly lower than with the swing design. In return there is an additional pressure drop equal to the spring force.
All moving parts are located in the centre body. The parts can be replaced by removing the centre body from between the ends.
The body and cover are steel; the sealing elements are PTFE. The part to be monitored is the spring.
Spring-loaded ball check valve (flanged), cross-section
Lift check valve
BLÇV · Cast iron · Flanged · PN 16 · DN 15 – DN 200
In a lift check valve the disc opens by rising perpendicular to its seat and is returned by a spring. It is suitable for lines carrying clean media.
The body and cover are cast iron; the disc and seat are stainless steel.
Lift check valve, cross-section
Which design for which line
| Condition | Suitable design | Reason |
|---|---|---|
| Pressure drop is critical, horizontal line | Swing | Pressure drop is low. |
| Pump line with frequent starts and stops | Spring-loaded ball · disc | The spring closes the valve the moment the flow stops; the risk of water hammer is reduced. |
| Restricted installation space | Disc | Fits between two flanges; slim and light. |
| Vertical line | Disc | Spring-loaded disc types can be used on both horizontal and vertical lines. |
| Pulsating flow (reciprocating pump discharge) | Spring-loaded designs | The instructions for use recommend the spring-loaded type on these lines. |
Sizing: a check valve is selected according to the operating flow rate, not the line size. In an oversized body the closing element remains partly open and chatters; this is the most common cause of premature failure in the field.
Installation direction and position
- The arrow on the body indicates the direction of flow. A check valve installed in reverse closes the line completely.
- Swing types operate on a horizontal line with the cover facing upwards.
- Spring-loaded disc types can be used on horizontal and vertical lines. On a vertical line the flow must be upwards.
- Sufficient straight pipe is allowed at the inlet. A check valve connected directly to an elbow or pump discharge chatters continuously in turbulent flow.
- A check valve is not a shut-off valve; it may permit slight leakage in the closed position. Where the line is to be isolated for maintenance, an isolation valve is used.
Inspection and maintenance
| Line | Inspection interval |
|---|---|
| Clean water, continuously operating line | Once a year: internal inspection of the body, seal renewal |
| Line with frequent starts and stops (pump discharge) | Every 6 months |
| Steam and condensate | Every 6 months |
| Medium with solid particles | Every 3 months |
Back leakage is caused in most cases by foreign matter lodged on the seat. If the pressure falls slowly when the line is stopped, the cleanliness of the seat is checked first. On spring-loaded types, spring fatigue delays closing; the spring length is checked on dismantling.
Applicable standards
| Design | Face-to-face dimension | Connection |
|---|---|---|
| Swing (cast iron, flanged) | EN 558 | EN 1092-2 |
| Lift (cast iron, flanged) | EN 558 | EN 1092-2 |
| Spring-loaded ball (steel, flanged) | EN 558 | EN 1092-1 |
| Spring-loaded ball (steel, threaded) | Batusan specific | EN 10226-1 |
| Disc | Batusan specific | Wafer |
Frequently asked questions
It depends on the design. A swing check valve is installed on a horizontal line with the cover facing upwards. A spring-loaded disc check valve can be used on horizontal and vertical lines; on a vertical line the flow must be from bottom to top.
The check valve design in which a hinged disc opens with the flow and returns to its seat when the flow stops. Pressure drop is low and it is used on horizontal lines. Details are given in the Swing check valve section.
A disc check valve is also spring-loaded: the spring presses the disc onto its seat. The difference lies in the body; it is a slim design installed between two flanges. In a spring-loaded ball check valve the closing element is ball shaped and the body is flanged or threaded.
The faster-closing design is selected. Spring-loaded types close markedly earlier than the swing type. If hammer persists at the pump discharge, soft start, slow stop or an air vessel are also considered.
No. A check valve only prevents backflow; it may permit slight leakage in the closed position. An isolation valve (for example a ball valve) is used to isolate the line.
See also
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