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Check Valves

The NozzleCheck is a non-slam check valve first developed in 1935. The first NozzleCheck valve installed in a nuclear power plant was in 1972; since then it has replaced over 800 conventional check valve designs.Specifically designed to combat damaging transients and water hammering, the NozzleCheck valve has been improving systems in some of the most demanding nuclear plant applications.

With a number of designs, NozzleCheck offers check valves for large and small bore, dirty, high capacity, and severe service applications.

In 1992, Curtiss-Wright Nuclear started manufacturing NozzleCheck valves under its Appendix B Program. Since that time, Curtiss-Wright Nuclear has been exclusively offering ASME Section III Class 1, 2, and 3, Safety-Related and Commercial NozzleCheck valves to the nuclear industry.

Want to see the NozzleCheck Valve in action? Download the Curtiss-Wright Augmented Reality App for iPhone on the Apple App Store, or schedule a live demo with our team today.

Models

DRV-Z | Small Bore, Axial Flow NozzleCheck Valve

The NozzleCheck DRV-Z is an axial flow, inline check valve. Similar to a conventional check valve, the DRV-Z allows forward flow under normal conditions, opens quickly with ease, firmly backseats at a low velocity and closes on a reverse flow with minimal seat leakage.

The DRV-Z provides a maintenance free design using minimal moving parts and a very short stroke to provide a rapid non-slam closure. This makes it a perfect choice for vertical and horizontal pipe configurations and is ideal for installations near sources of turbulence such as elbows, reducers, pumps and orifices. The DRV-Z model is well suited for small bore applications protecting critical equipment from reverse flow, containment isolation of pressure boundary penetrations, excessive tank vacuum and high energy line break isolation.

Key Features and Benefits

Short Stroke length	Extremely quick closure
Low Mass Disc	Non-slam closure, eliminating water hammer induced damage
Spring loaded disk	Allows mounting in any orientation
Conical seating surface	Self-aligning seat, provides tight shutoff
Integral disk/stem construction	Rigid structure to handle severe turbulence, eliminates flutter
Low friction bushing surface, no hinge pins	No scheduled maintenance, long service life

Principles of Operation

The DRV-Z small bore axial flow inline check valve is able to allow full forward flow under normal operation. As forward flow velocity reduces to a specified minimum (Vmin), the spring assisted disk firmly closes, preventing reverse flow. The DRV-Z employs a streamlined diffuser that minimizes pressure loss. A disk/stem assembly also provides a rigid structure within a low friction surface to minimize wear. Disk closure relies on differential pressure with assistance from the spring. The DRV-Z can be selected for applications with a specified V_min or opening pressure to meet system requirements.

General Specifications

Size:	3/4" - 10"
Ratings:	ANSI Pressure Class 150 to 2500
Connections:	Flanged, Socket or Butt Weld
Quality Class:	Commercial, Safety-Related, ASME Code, Class 1, 2, 3

Plant Design

PWR, BWR, CANDU

Typical Plant Applications

Auxiliary Feedwater Steam Supply System
RCIC Turbine Exhaust
Pressure Boundary/Containment Isolation
Safety Injection System
Instrument Air Systems
Tank/vessel vacuum protection
High Energy Line Breakage Isolation
GL 89-04 Safety Related Applications

NozzleCheck DRV-Z axial flow, inline check valve

DRV-B | Large Bore, Axial Flow NozzleCheck Valve

The DRV-B is used for large bore check valve applications where high capacity is required. It has a donut shaped disc allowing flow through the inside and outside of the disc. The disc is free floating and does not rely on the alignment of any guiding surface for proper seating. Large bore axial flow check valve.

The DRV-B typically uses 3 helical springs to control the closing speed and apply additional seat load under low differential pressure conditions. The DRV-B has a diffuser that allows a smooth transition of areas reducing pressure loss and creating a low-pressure area behind the disc to create sufficient force to fully open the valve.

Key Features and Benefits

Short Stroke, Spring Assist and Low Mass Disc	Ability to close quickly, eliminating waterhammer
Dynamic Testing Complete	Proof of speed of response, no other axial flow check valve has had these curves tested and documented
Two Flow Paths Around Disc	Higher capacity than other axial flow check valves
Tight Seating in High Differential Pressure Flow Vertical Installation	Low seat leakage improved operational efficiency
Diffuser	Smooths flow transition while minimizing pressure loss

Principles of Operation

The DRV-B is installed to allow flow in only one direction. As pressure is reduced on the inlet side compared to the outlet, flow will reduce. When the flow is reduced to a point, depending on the spring strength, the valve will start to close. It will fully close at nearly the zero flow condition. Three or four helical springs are used, depending on valve size, to provide a closing force. Springs are sized to be strong enough to close quickly to eliminate waterhammer and weak enough to allow full open operation during normal operating modes.

General Specifications

Size:	12" to 72"
Ratings:	ANSI Pressure Class 150 to 1500
Connections:	RFF, RTJ, BW
Quality Class:	Commercial, Safety-Related, ASME Section III

Plant Design

PWR, BWR, CANDU

Typical Plant Applications

Feed Pump Discharge
Feed Header
Component Cooling Water Pump Discharge
Service Water Pump Discharge
Heater Drain Pump Discharge
Extraction Steam
Cooling Water Pump Discharge
Condensate and Condensate Booster Pump Discharge
SFP Pump Discharge

NozzleCheck DRV-B large bore check valve

DRV-BK | Large Bore, Short Face-to-Face NozzleCheck Valve

The DRV-BK is used for large bore check valve applications where a narrow face-to-face is required. It has a donut shaped disc allowing flow through the inside and outside of the disc. The disc is connected to a center shaft.

The DRV-BK has one helical spring enclosed within the center body section to control the closing speed and apply additional seat load under low differential pressure conditions. The DRV-BK does not have a diffuser like the DRV-B and DRV-Z.

Key Features and Benefits

Short Stroke, Spring Assist and Low Mass Disc	Ability to close quickly, eliminating waterhammer
Dynamic Testing Completed and Documented	Proof of speed of response, no other check axial flow has had these curves tested and documented
Two Flow Paths around Disc	Higher capacity than other axial flow check valves
Tight Seating in High Differential Pressure Flow Up Vertical Installation	Low seat leakage

Principles of Operation

The DRV-BK is installed to allow flow in only one direction. As pressure is reduced on the inlet side compared to the outlet, flow will reduce. When the flow is reduced to a point, depending on the spring strength, the valve will start to close. It will fully close at nearly the zero flow condition. The center spring provides a closing force. Springs are sized to be strong enough to close quickly to eliminate waterhammer and weak enough to allow full open operation during normal operating modes.

General Specifications

Size:	12" to 72"
Ratings:	ANSI Pressure Class 150 to 1500
Connections:	RFF, RTJ, BW, Lugged and Wafer
Quality Class:	Commercial, Safety-Related, ASME Section III

Plant Design

PWR, BWR, CANDU

Typical Plant Applications

Component Cooling Water Pump Discharge
Service Water Pump Discharge
Extraction Steam
Cooling Water Pump Discharge
Condensate and Condensate Booster Pump Discharge
SFP Pump Discharge

NozzleCheck DRV-BK large bore check valve

DRV-N | Normally Open NozzleCheck Valve

In some applications the fluctuation in pressure, downstream leaks, or other phenomena can result in constant chatter of a check valve causing hinge pin wear or damage to the seating surface. The DRV-N, Normally Open NozzleCheck valve, has been designed to withstand the rigors of these types of applications.

Principles of Operation

This particular design has a similar body configuration to the Model DRV-Z, but rather than a normally closed design that is opened using system pressure, the disc in the DRV-N is opened using a spring. As a result, the valve is unaffected by pressure changes and the problem of constant cycling is avoided. Furthermore, the DRV-N employs the use of a stem guide rather than a diffuser. This feature provides a less congested flow path so that the backpressure can effectively close the valve when flow exceeds normal levels. When closed, the disc is self-aligning and finds the best seating position to form a tight shutoff.

General Specifications

Sizes:	½” – 12”
Pressure Class:	ANSI Pressure Class 150 to 4500
Body Type:	Flanged, Butt Weld, and Socket Weld

Plant Design

PWR, BWR, CANDU

Typical Plant Applications

AFPT Steam Supply
Applications with Fluctuation in Pressure

Available NozzleCheck Products

DRV-Z Small Bore
DRV-B Large Bore
DRV-BK Large Bore, Short Face
KRV-B Large Bore, Short Face
DRV-N Normally Open
XRV Specially Engineered