NRS Gate Valve

Non-Rising Stem (NRS) Gate Valve is a type of gate valve where the stem does not move up or down as the valve is operated. Instead, the gate itself moves up and down along the stem. This design is beneficial in applications where space is limited.

SPECIFICATIONS

NRS Resilient Seated Gate Valve Flanged Ends PN10/16 BS5163 DINF4/F5

Face To Face Standard: EN558,(DIN3202 F4/F5, BS5163, SABS664/665)

Design Standard: BS EN1171/EN1074-2

Flanges Standard: BS EN1092-2

Inspection & testing: BS EN 12266-1

(Other Flange Types available on request)

(ISO Top Flange, Indicator available on request)

Fusion Bonded Epoxy Powder Coated Interior and Exterior to EN14901

USE

Working Pressure: 16bar

Working Temperature: -20℃ to 100℃

Operator: Hand wheel, Operating Nut,Gearbox,Extension Spindle

Drawing

Non Rising Stem Gate Valve Drawing

Material specification

No	Part	Material
1	Body	Ductile Iron
2	Wedge	DI & EPDM
3	Wedge Nut	Brass
4	Bonnet	Ductile Iron
5	Stem	SS420 (1.4021)
6	Gland	Brass
7	Handwheel	Ductile Iron
8	Bonnet Gasket	NBR/EPDM
9	Bonnet /Gasket Bolt	CS With ZINC Plated/SS304
10	Wedge Nut Gasket	NBR/EPDM
11	Washers	Nylon/Brass
12	O-ring	NBR/EPDM
13	Dust Cap	NBR/EPDM
14	Handwheel Bolts	SS304 (1.4301)

DIMENSIONS(mm) BS EN1092-2 PN10/16

DN	L				H	D	C		M		b	f	W	n-d
	F4	F5	BS5163/665	664			PN10	PN16	PN10	PN16				PN10	PN16
40	140	240	165		205	150	84	84	110	110	19	3	160	4-19	4-19
50	150	250	178	216	258	165	99	99	125	125	19	3	160	4-19	4-19
65	170	270	190		262	185	118	118	145	145	19	3	160	4-19	4-19
80	180	280	203	229	305	200	132	132	160	160	19	3	200	8-19	8-19
100	190	300	229	254	350	220	156	156	180	180	19	3	250	8-19	8-19
125	200	325	254		364	250	184	184	210	210	19	3	280	8-19	8-19
150	210	350	267	280	436	285	211	211	240	240	19	3	300	8-23	8-23
200	230	400	292	317	535	340	266	266	295	295	20	3	350	8-23	12-23
250	250	450	330	356	634	405	319	319	350	355	22	3	400	12-23	12-28
300	270	500	356	380	721	460	370	370	400	410	24.5	4	480	12-23	12-28
350	290	550	381	470	783	520	429	429	460	470	26.5	4	560	16-23	16-28
400	310	600	406	470	902	580	480	480	515	525	28	4	560	16-28	16-31
450	330	650	432	485	980	640	530	548	565	585	30	4	750	20-28	20-31
500	350	700	457	510	1092	715	582	609	620	650	31.5	4	750	20-28	20-34
600	390	800	508	600	1275	840	682	720	725	770	36	5	750	20-31	20-37
700	430	900	610		1513	910	794	794	840	840	39.5	5	950	24-31	24-37
800	470	1000	660		1663	1025	901	901	950	950	43	5	950	24-34	24-41
900	510	1100	711		1837	1125	1001	1001	1050	1050	46.5	5	1050	28-34	28-41
1000	550	1200	811		2050	1255	1112	1112	1160	1170	50	5	1050	28-37	28-44

Working Principle

In a Non-Rising Stem (NRS) Gate Valve, the transmission between the threads on the stem and the stem nut (commonly referred to as the gate or gate nut) is a critical part. Here’s how the transmission works in detail:

The structure of the stem and gate nut:

Stem: The stem has an external thread.
Gate nut: The nut on the gate or connected to the gate has an internal thread that mates with the external thread of the stem.
The transmission process:Connecting the handwheel and stem: The handwheel is secured to the top of the stem with a key or pin. When the handwheel turns, the stem turns.
Connecting the stem to the body: The stem is connected to the body by a packing box or other fixed device, ensuring the stem can only rotate and not move axially.
Operating the valve:

Closing the valve:Turn the handwheel clockwise, which turns the stem clockwise.Because the stem is fixed (it can only rotate), the external thread on the stem pushes the gate nut down the thread.The gate nut is connected to the gate, which moves down, closing the flow path until it’s fully closed.
Opening the valve:Turn the handwheel counterclockwise, which turns the stem counterclockwise.The external thread on the stem pushes the gate nut up the thread.The gate nut moves the gate up, opening the flow path until it’s fully open.

Sealing and protection:The stem is sealed to the body by the packing box or O-ring to prevent fluid from leaking.The resistance provided by the packing box ensures the stem doesn’t move axially when it rotates.
Advantages:

Space-saving: NRS designs are very useful in applications with limited space because the stem doesn’t rise or fall.
Thread protection: The stem threads aren’t exposed to the environment, reducing the risk of corrosion and damage.
Disadvantages:Greater operating force: Because of the threaded transmission, more force is required to turn the handwheel and the stem, especially in high-pressure applications.
In summary, in an NRS Gate Valve, the threads on the stem and gate nut are transmitted through the rotation of the handwheel to move the gate up and down to control the flow of fluid. This design takes advantage of the mechanical advantages of threaded transmission, ensuring the stem remains fixed, and is suitable for a variety of industrial and municipal applications.

NRS Gate Valve VS OS&Y Gate Valve

NRS Gate Valve (Non-Rising Stem Gate Valve) and OS&Y Gate Valve (Outside Screw and Yoke Gate Valve) each have their own advantages and disadvantages and are suitable for different applications. Here are the pros and cons of NRS Gate Valve compared to OS&Y Gate Valve:

Pros of NRS Gate Valve:

Space-saving:No extra vertical space: The stem doesn’t rise or fall during operation, making it great for installing underground or in tight spaces like underground piping or inside buildings.

Protecting the stem threads:Internal protection: The stem threads are inside the valve body and aren’t exposed to the outside environment, reducing the risk of corrosion and wear.

Safe operation:Less external damage: Because the stem isn’t exposed, there’s less chance of the stem getting damaged from external impacts or physical damage, adding to the safety of operation.

Cost-effective:Usually cheaper: Designing and manufacturing an NRS valve is usually cheaper than an OS&Y valve, so it’s usually cheaper on the market.

Cons of NRS Gate Valve:

Difficult to tell the valve’s position:Can’t tell if the valve is open or closed at a glance: Because the stem doesn’t rise or fall, it’s hard to tell if the valve is open or closed just by looking at it. You need to rely on markings or additional indicators.

Requires more force to operate:Higher operating force: Because of the thread friction between the stem and the gate, you might need more force to operate it, especially in high-pressure environments.

Complex maintenanceMaintenance of internal threads: The stem threads are inside the valve body, making maintenance and lubrication more difficult. You have to check and maintain them regularly to ensure long-term, reliable operation.

Pros of OS&Y Gate Valve:

Intuitive position indication:Easy to tell the valve’s position: The stem rises and falls as the valve opens and closes, so the operator can see at a glance whether the valve is open or closed.

Requires less force to operate:Less force required: Because the stem directly lifts or lowers the gate, there’s less friction, so it requires less force to operate, making it easier to operate.

Better sealing:External thread design: The threads are on the outside of the valve body, so the sealing is usually better, making it good for applications that require a tight seal.

Cons of OS&Y Gate Valve:

Takes up more space:Requires extra vertical space: The stem rises when it opens, taking up more vertical space, so it’s not good for tight spaces.

Exposed threads:Exposed threads can be damaged: The stem threads are exposed, making them vulnerable to the environment, like corrosion, dust, and physical damage, so they need more maintenance and protection.

Conclusion:Whether you choose an NRS Gate Valve or an OS&Y Gate Valve depends on your specific application requirements and installation environment. If you’re tight on space and need to protect the stem threads, an NRS Gate Valve is a good choice; if you need to see at a glance whether the valve is open and requires less force to operate, an OS&Y Gate Valve might be the better choice.

Application

Based on the pros and cons of NRS Gate Valve, here are some scenarios where an NRS Gate Valve is a good fit and the reasons why:

Good for:

Underground installation Why: Because the stem doesn’t rise or fall during operation, an NRS Gate Valve is great for installing in underground piping. It avoids installation difficulties caused by vertical space limitations.

Tight spaces Why: An NRS Gate Valve doesn’t need extra vertical space for the rising stem, making it great for tight spaces like inside buildings, underground facilities, well houses, etc.

Water supply and sewage treatment systems Why: In these systems, you typically have lots of valves controlling water flow, and the compact design and lower cost of an NRS Gate Valve make it an economically efficient choice.

Fire protection systems Why: An NRS Gate Valve is often used in control valves in fire protection systems because of its compact design and reliable sealing to ensure quick and effective operation in emergencies.

Underground and wellhead applications Why: With the stem threads inside the valve body, the risk of corrosion and physical damage is reduced, making this a good fit for harsh underground and wellhead environments.

Not good for:

Where you need to visualize the valve’s position Why: Because you can’t tell at a glance whether an NRS Gate Valve is open or closed, you might need additional indicators or markings in these scenarios, adding complexity to operation.

High-pressure systems Why: In high-pressure systems, the NRS Gate Valve requires more force to operate, making it less easy to operate than other designs, especially in cases where you need to operate it frequently.

Places exposed to harsh environments Why: Even though the threads are inside an NRS Gate Valve, in applications that require frequent maintenance, maintaining the threads inside can be relatively difficult, requiring regular inspection and upkeep.

In summary:NRS Gate Valve works great in underground installations, tight spaces, water supply and sewage treatment systems, and other applications that require a compact design and lower cost. Its design advantages are in saving vertical space and protecting the stem threads, giving it great performance in these environments. However, in places where you need to visualize the valve’s position or high-pressure systems, you might want to consider other types of valves. Choosing the right valve type requires a balance between your specific application requirements and environmental conditions.

NRS Gate Valve Manual

To properly operate a Non-Rising Stem (NRS) Gate Valve, you need to follow these steps to ensure the valve operates correctly and has a long service life:

Steps to operate:

Preparation

Inspect the valve: Before operating, inspect the valve’s exterior to make sure there are no obvious signs of damage or leaks.

Lubrication: If the valve has a lubrication device, make sure it’s adequately lubricated to reduce friction during operation.

Clean: Remove any debris around the valve and handwheel to make sure the operation area is clean and unobstructed.

Opening the valve:Turn the handwheel clockwise: Slowly and evenly turn the handwheel clockwise to make sure the stem and gate gradually descend until the valve is fully closed.

Watch your force: Don’t use excessive force to turn the handwheel to avoid damaging the stem or internal threads.

Check the condition: After the valve is fully closed, check the valve’s seal to make sure there are no leaks.

Closing the valve:Turn the handwheel counterclockwise: Slowly and evenly turn the handwheel counterclockwise to make sure the stem and gate gradually ascend until the valve is fully open.

Watch your force: Similarly, don’t use excessive force to turn the handwheel to avoid damaging the valve.

Check the condition: After the valve is fully open, check the flow through the valve to make sure there are no obstructions.

Precautions:

Even force:Apply even force to the handwheel to avoid sudden or rapid turns, which protect the stem threads and the valve’s internal structure.

Regular maintenance:Regularly check and lubricate the stem threads to make sure they operate smoothly.Check the packing box or seal, and replace as necessary to prevent leaks.

Use the correct tools:Use the correct size handwheel or wrench to operate the valve; don’t use a tool that’s too large and could cause you to use too much force.

Prevent misoperation:Install operation labels or indicators to make sure the operator can clearly identify the valve’s open or closed status to avoid misoperation.

Regular testing:Regularly perform function tests to make sure the valve can open and close correctly when needed, especially in critical applications like fire protection systems.

Conclusion:To properly operate an NRS Gate Valve, you need to operate it carefully and evenly, perform regular maintenance and checks, and use the correct tools and methods. By following the steps and precautions above, you can ensure the valve operates correctly and has a long service life.

NRS Gate Valve Maintenance

Maintaining an NRS Gate Valve is crucial to ensure its long service life and proper operation. Here are the maintenance requirements and common maintenance procedures for an NRS Gate Valve:

Maintenance requirements:

Regular inspection:Inspect the valve’s exterior and structure to make sure there are no obvious signs of damage, corrosion, or leaks.

Check to see if the valve operates smoothly without sticking or strange noises.

Lubrication:Regularly lubricate the stem threads and other moving parts to reduce friction and wear and ensure smooth operation of the valve.

Use the appropriate lubricant, typically a waterproof and anti-corrosive grease, suitable for the valve’s materials and working environment.

Seal inspection:Regularly check the condition of the packing box or seal to ensure there are no leaks.

If the packing or seal is found to be worn out or aged, replace it promptly.

Function testing:Regularly perform open and close tests on the valve to ensure the valve can open and close correctly, especially in critical applications like fire protection systems.

Common maintenance procedures:

Lubricating the stem threads:

Steps:

Close the valve and make sure the system has no pressure.

Use the appropriate tool, such as a wrench, to remove the protective cover or handwheel at the top of the stem.

Apply the recommended lubricant to the stem threads, making sure the lubricant covers the entire threaded portion evenly.

Reinstall the handwheel or protective cover, making sure it’s securely fastened.

Checking and replacing the packing box or seal:

Steps:

Close the valve and make sure the system has no pressure.

Use the appropriate tool to loosen the packing box gland nut.

Remove the old packing or seal and check its condition.

Replace the old packing or seal as necessary, making sure it’s installed correctly.

Tighten the packing box gland nut, but don’t overtighten it, as it could affect the operation of the stem.

Valve function testing:

Steps:

Gradually open and close the valve, observing whether the valve operates smoothly without sticking or making strange noises.

Check the valve’s sealing to make sure there are no leaks when it’s closed.

If problems are found, promptly repair or replace the damaged parts.

Corrosion and damage inspection:

Steps:

Regularly inspect the valve’s exterior and interior for corrosion, wear, or mechanical damage.

For areas with corrosion, you can repair them with an anti-corrosion coating.

Severely damaged parts should be replaced promptly to ensure the valve operates properly.

In summary:By performing regular checks and maintenance, including lubricating the stem threads, checking and replacing seals, function testing, and anti-corrosion treatments, you can ensure the reliability and long service life of an NRS Gate Valve. Timely maintenance and upkeep can effectively reduce the failure rate and improve the overall operational efficiency of the system.