“Please quote 20 DN250 NBR butterfly valve seals.”
That sounds like a straightforward purchasing request. The maintenance team knows the valve diameter, the stores department has an old rubber ring, and production wants the replacement delivered quickly.
Yet one essential detail is missing: which sealing ring actually fits the installed valve?
For a VFS-family powder butterfly valve, DN and NBR identify the nominal size and elastomer family, but they do not establish the exact replacement part. The sealing ring must fit the valve-body seat and work with the disc that closes against it.
This becomes especially important when the original part number is missing, several valve configurations are used at one plant, or the removed seal is already damaged.
The purchasing task is to identify the correct internal component before the order is confirmed.
Why “DN250 NBR” Is Not a Complete Part Number
DN250 identifies the valve’s nominal diameter. NBR identifies the general rubber material.
Neither tells the supplier the complete shape of the molded sealing ring, its seating profile, or the disc edge it is intended to contact.
A maintenance storeroom may contain several boxes marked “DN250 rubber seal.” Those descriptions can look identical even when the parts were originally supplied for different valve assemblies.
Four details need to agree before a replacement sealing ring can be confirmed:
Valve identification: The correct valve family, size and configuration.
Disc interface: The material and mating-edge arrangement of the rotating disc.
Seal geometry: The ring profile and its relationship with the valve-body seating groove.
Material specification: The elastomer properties required for the installed valve and operating conditions.
A shared nominal diameter or rubber description is useful for narrowing the search. It is not proof that two replacement rings are interchangeable.
Read the Valve Code Before Measuring the Old Ring
The most useful starting point is the complete valve model.
Check the identification marking, original purchase record, maintenance history or equipment drawing before relying on measurements taken from a worn seal.
For TONGJINJIN powder butterfly valves, VFS, V1FS and V2FS identify different body and connection arrangements. The model suffix provides information about the internal components.
Consider two configurations.
V2FS250SN
V2FS: Double-flange butterfly valve
250: DN250 nominal diameter
S: Polyurethane disc
N: NBR sealing ring
The configuration can be checked against the V2FS Butterfly Valve-SN.
V2FS250GBN
V2FS: Double-flange butterfly valve
250: DN250 nominal diameter
GB: Nodular cast iron disc
N: NBR sealing ring
The corresponding configuration is the V2FS Butterfly Valve-GBN.
Both models have the same nominal diameter and use NBR sealing rings. Their disc materials are different.
That distinction does not automatically prove whether their replacement sealing rings are identical or different. The correct part must be established from verified part identification or dimensional information.
The same care applies when identifying a single-flange valve such as the V1FS Butterfly Valve-SN.
What if DN Is the Only Reliable Information?
If the original model cannot be identified, use DN as a preliminary size reference—not as confirmation of the replacement part.
A supplier may be able to provide an initial price indication, but the exact sealing ring should remain unconfirmed until the installed valve, disc and sealing seat have been identified.
Useful evidence includes:
Photographs showing the complete valve-body arrangement.
Images of the disc edge and sealing seat.
Measurements from accessible, undamaged areas.
The removed ring, if available.
Previous purchase records or drawings.
If this information is insufficient, the next step may be comparison with an identified sample or verified component specification.
An unidentified ring should not become a confirmed bulk order simply because its diameter appears correct.
The Removed Seal Is Evidence, Not the Master Dimension
When the model marking is missing, the old sealing ring may be the only removable part available for examination.
It is valuable evidence, but it is not necessarily an accurate representation of the original dimensions.
After service, an elastomer ring can develop:
Flattened contact areas.
Cuts or damaged sealing lips.
Permanent deformation.
Local swelling or distortion.
Uneven wear around its circumference.
A measurement taken from a damaged section may differ from the intended dimensions of a new part.
The relationship between the removed ring, the valve-body seating groove and the rotating disc matters more than a single outside-diameter measurement.
Where the equipment has been safely isolated and qualified personnel can access the components, record the condition of all three.
Never dismantle a valve beneath a loaded or pressurized outlet merely to obtain a spare-parts measurement.
Measurements from the used ring can help narrow the identification, but the replacement should ultimately be checked against a verified drawing, part specification or confirmed sample fit.
A supplier should not be asked to manufacture a precise replacement from an uncertain measurement of damaged rubber.
Four Photographs That Make a Seal Inquiry Useful
A supplier does not necessarily need dozens of photographs.
Four carefully selected views can provide the information needed to investigate a replacement.
1. Complete Valve and Identification Marking
Photograph the complete butterfly valve and any readable model designation.
Include enough of the body to distinguish between VFS, V1FS and V2FS configurations.
If the marking is damaged or missing, photograph the relevant body features instead of guessing the model.
2. Disc Material and Mating Edge
Provide a clear view of the disc and the area that contacts the sealing ring.
The disc material and contact profile help the supplier understand which internal component the replacement must fit.
If the disc material is uncertain, state that in the inquiry.
3. Valve-Body Sealing Seat
When safe access is available, photograph the groove or seating area inside the valve body.
This view is particularly useful when the removed rubber ring is severely deformed.
The internal seat provides information that cannot be obtained from an exterior photograph of the flange.
4. Removed Sealing Ring With a Scale
Photograph the entire ring and its cross-section.
Include a ruler or caliper for scale, and identify any sections affected by visible wear or damage.
Do not stretch or distort the ring simply to make it fit the photograph.
If the valve has not yet been dismantled, provide its identification and available maintenance records first. A preliminary matching check may be possible without immediate removal.
The objective is to preserve reliable information about the existing assembly—not to collect measurements that appear precise but cannot be trusted.
Turn the Enquiry into a Checkable Spare-Parts Quote
Consider the original request:
“DN250 NBR seal, 20 pcs.”
It tells the supplier the approximate product category and required quantity, but not enough to identify the exact spare part.
A more useful request separates the information available at the plant from the details the supplier must verify.
Information from the buyer | What the supplier needs to confirm |
|---|---|
Full valve model or identification photographs | Correct valve family and configuration |
Disc material or clear disc-edge photograph | Matching sealing interface |
Old ring and valve-seat photographs | Ring profile and seating arrangement |
Measurements, where available | Dimensional compatibility |
Handled powder and operating conditions | Appropriate seal-material specification |
Existing part number or purchase reference | Identification against the required spare |
Quantity and requested supply scope | Ring-only or additional matched components |
A practical inquiry can be written as follows:
Subject: Replacement Sealing Ring Enquiry — V2FS250SN — 20 pcs
We require 20 replacement internal sealing rings for the installed butterfly valves shown in the attached photographs.
The valve marking reads V2FS250SN. The handled material is dry cement powder.
Please confirm the correct sealing-ring specification and whether the quotation covers the ring only.
We can provide additional photographs and measurements of the existing sealing seat if required.
If the model is unknown, replace the model reference with model not identified and explain which supporting information is available.
A clear statement of uncertainty is more useful than an assumed part number.
This allows the supplier to distinguish a preliminary enquiry from a confirmed replacement order.
Check the Scope Before Approving the Order
The term butterfly valve seal can describe different components.
The internal sealing ring forms the seating contact with the rotating disc.
An external flange gasket seals a connection between the valve and adjoining equipment.
They perform different functions and should be identified separately in a purchase request.
Before approving an internal sealing-ring order, check that the quotation states:
The applicable valve model or verified spare-part reference.
The specified sealing material.
Any required compound or dimensional specification.
Whether the supply includes the sealing ring alone.
Whether a replacement disc is included or quoted separately.
The ordered quantity and package identification.
The drawing or approved sample reference, when used for matching.
An order for the correct rubber material can still be unsuitable if the molded profile does not match the installed assembly.
For plants maintaining several butterfly valve configurations, keep the spare-part identification on the packaging.
A label stating only “DN250 NBR” may create the same uncertainty during the next maintenance operation.
The purpose of these checks is simple: make sure the part delivered is the part the maintenance team can actually install.
The Best Replacement Order Names the Mating Parts
A successful butterfly valve seal replacement begins with identifying the installed assembly.
When the original model is known and the internal configuration remains unchanged, it provides the most useful starting reference.
When the model is missing or the valve has previously been modified, photographs, measurements, maintenance records and an approved sample may be needed to establish the correct part.
For VFS-family powder valves, TONGJINJIN can review the available information and confirm whether a matching replacement NBR sealing ring can be supplied separately.
The strongest purchasing request does more than state a diameter and quantity.
It identifies the valve, the mating components and the information used to establish compatibility.
That reduces the risk of ordering a rubber ring that looks correct but does not fit the actual valve.
Butterfly Valve Seal Replacement
- Frequently Asked Questions
No. NBR identifies an elastomer family, not one universal rubber compound or hardness.
Different formulations may have different mechanical properties and service limitations.
When ordering a replacement, the supplier should confirm the material specification associated with the verified sealing-ring part.
Selecting rubber solely because it is described as NBR does not establish an equivalent replacement.
Yes, provided the invoice contains a traceable spare-part reference and the installed valve configuration has not changed.
Check that the replacement is intended for the same valve model, disc arrangement and applicable component version.
A previous invoice is particularly helpful when the original valve marking is difficult to read.
However, an invoice describing only “DN250 rubber seal” may not provide enough information to establish the correct part.
The original valve marking may no longer describe every component currently installed.
If a disc was replaced with a different configuration, the sealing-ring requirement must be checked against the actual disc and valve-body seat.
Provide the replacement disc’s identification or photographs showing the installed arrangement.
Do not assume that the original model suffix alone establishes the correct spare after internal modifications.
Often, yes.
A complete model number, previous purchase reference and clear photographs may allow the supplier to identify a likely replacement and provide an initial quotation.
If the internal configuration cannot be verified, the quotation should make clear that final part confirmation remains pending.
This allows procurement to begin without treating an unverified component as an approved replacement.
When the exact part identity is uncertain, checking an approved sample before confirming a bulk order can reduce purchasing risk.
The sample should be compared with the verified valve assembly and assessed for the required fit by qualified personnel under safe maintenance conditions.
The supplier should also confirm the material specification and part identification.
Once the correct replacement is established, retain that reference for future orders rather than repeating the identification process from the beginning.
