Description
Connect a one-inch fitting
A compact brass tank reducer with a 1¼-inch BSP external male thread and a 1-inch BSP internal female thread.
The short body has a hexagonal base. One brass back nut and one black sealing washer are included.
For a compatible tank mounting and a separately chosen tap or connector.
Check the outside and inside threads
The labelled photograph identifies the two connections: 1¼-inch BSP male around the outside and 1-inch BSP female through the centre.
For a tank with an existing thread, the outer male side needs a matching 1¼-inch BSP female outlet. The internal thread accepts a separately purchased one-inch BSP male tap or connector.
These are nominal BSP sizes. They identify the threads rather than the hose bore. Check the fitting at each connection so the reducer suits the complete setup.
Plan the mounting before drilling
Check the wall seal, retaining nut and tap connection together.
Check the opening
The mounting-hole guide for this adapter is 42mm. Confirm this against the actual fitting and tank before drilling. Check that the wall thickness and shape allow the washer to seat and the nut to engage.
Seat the washer and nut
Position the black washer against the connector’s base at the tank wall, with the back nut retaining the fitting on the opposite side. Hold the body while tightening and avoid distorting the wall or washer.
Finish the threaded connection
Attach a matching male fitting to the internal thread with a suitable sealing arrangement for that joint. The wall washer seals the tank mounting; inspect that seal and the separate fitting connection for leakage before use.
Questions about the larger reducer
What does 1.25-inch BSP mean on this adapter?
It is another way of writing 1¼-inch BSP, the external male thread size. The internal female thread is one-inch BSP. Check these two nominal thread designations against the tank outlet and the fitting you intend to connect.
Is the back nut supplied separately from the body?
Yes. The pack includes one brass adapter body, one removable brass back nut and one black sealing washer. The original exploded product photo shows the nut above the body to identify the parts; it is refitted when assembling the mounting.
What hole size should I check for a new tank outlet?
The mounting guide is a 42mm hole. Check the actual connector, tank wall thickness and shape before drilling. You also need a suitable sealing surface and enough access to position the washer and tighten the retaining nut.
Does it include a tap or hose connection?
No. One adapter body, one back nut and one washer are supplied. Choose a separate fitting with a matching one-inch BSP male inlet, then match its outlet to your hose or dispensing arrangement. Check clearance and sealing for the complete assembly.
Product information & technical details
| SKU | WB-BR-1BSPF-125BSPM001 |
|---|---|
| Product type | |
| BSP thread size | 1", 1.25" |
| Thread gender | Male, Female |
| Colour | Brass |
| Material | Brass |
| External male thread | 1.25-inch BSP male |
|---|---|
| Internal female thread | 1-inch BSP female |
| Back nut | 1 brass nut included |
| Sealing washer | 1 black washer included |
| Mounting-hole guide | 42mm; check actual fitting before drilling |
| Supplied contents | 1 adapter, 1 back nut and 1 washer |
What is BSP?
What is BSP thread size?
BSP (British Standard Pipe) is a nominal pipe-thread size, not a direct measurement of a fitting’s bore or outside diameter. For example, a ½-inch BSP male thread measures about 21mm across its outer thread crests.
These figures are approximate outside diameters of male BSP threads, to help identify the nominal size. They are not inch-to-millimetre unit conversions:
- 3/8" BSP → 16.66 mm
- 1/2" BSP → 20.95 mm
- 3/4" BSP → 26.44 mm
- 1" BSP → 33.25 mm
- 1.25" BSP → 41.91 mm
- 1.5" BSP → 47.80 mm
- 2" BSP → 59.61 mm
- 3" BSP → 87.88 mm
- 4" BSP → 113.03 mm
All our BSP threads are parallel (BSPP, to ISO 228), not tapered.
Measure across the outside of a male thread, then check its pitch and whether it is parallel or tapered. Diameter alone does not confirm compatibility. Check the product’s stated thread specification before connecting.
All delivery times are estimates and not guaranteed. Orders placed before 1 pm, Monday to Friday (excluding bank holidays), will be dispatched the same day, while orders placed after 1 pm will be dispatched by the end of the next working day.
If an invalid postcode or address is provided, the order will be cancelled without further notice, as we are unable to modify addresses or print labels for invalid postcodes.
Our standard delivery option is Royal Mail Tracked 48, which typically takes 3–5 business days. If you need your order more quickly, Expedited delivery via Royal Mail Tracked 24 is available, offering a 1–2 business day service.
Large or bulky items may be sent via courier at our discretion and are usually dispatched for next-day delivery. Please note that we only ship to mainland UK addresses; delivery to non-mainland locations, including the Highlands & Islands, may not be available for large or heavy items. If your address falls into one of these areas and you wish to purchase such items, please contact us with your postcode and order details before placing your order. If we cannot ship to you, you are welcome to arrange your own courier for collection.
All products, unless otherwise stated, come with a standard manufacturer warranty against faulty workmanship.
If your product fails within six months of delivery, please contact us with your order reference number, a description of the issue, and clear images illustrating the fault.
Should your item require a return for further investigation, it is your responsibility to arrange and cover postage back to us.
If we are unable to repair the fault, we may offer either a replacement or a full refund.
In cases where the item is inspected and found not to be faulty, or where damage is determined not to be due to manufacturing defects, you will not be entitled to a refund or replacement. We will then either return the item to you via standard post or dispose of it at your request.
You may return any order within 14 days of delivery. As soon as you receive your items, please inspect them carefully, taking reasonable care to keep both the product and its packaging clean and undamaged. If you discover an error or defect after 14 days, we reserve the right to decline your return. If your product fails or breaks after this 14-day time window then your order may be eligible for a warranty claim, please see our warranty information for more details.
To initiate a return, please contact us via our contact form to obtain a return authorisation and the correct returns address (different from the address on your invoice). This can also be done through your 'recent orders' page on your account if you are registered with Shop. Returns sent without prior authorisation will be discarded.
Returned items must be in the same condition in which you received them: unworn or unused, with tags attached and in their original packaging. You must include either a copy of your invoice or a slip with your order reference number inside the parcel. Please be sure not to obscure your return reference number on the label.
If you refuse delivery or reject the parcel without prior notice, we will inspect the returned package and issue a refund upon receipt. Although there is no restocking fee, we will deduct the cost of the return postage label (£3.35) from your refund.
If the returned item or its packaging shows signs of use, damage, or staining, we may deduct up to 50% of the order value, or refuse the return entirely, depending on its condition. Examples include damaged tags, stained, modified or damaged packaging, or missing components.
For faulty, incorrect, or damaged items, please contact us before sending anything back so we can attempt to resolve the issue directly. If we agree that a return is necessary due to our error, we will provide you with a pre-paid return label.
Products that have been modified or damaged through customer action are not eligible for return. This includes, but is not limited to, items that have been cut, trimmed or otherwise altered (such as a tarpaulin or pond liner resized to your specifications), or any product showing damage beyond normal inspection handling.
All delivery times are estimates and not guaranteed. Orders placed before 1 pm, Monday to Friday (excluding bank holidays), will be dispatched the same day, while orders placed after 1 pm will be dispatched by the end of the next working day.
If an invalid postcode or address is provided, the order will be cancelled without further notice, as we are unable to modify addresses or print labels for invalid postcodes.
Our standard delivery option is Royal Mail Tracked 48, which typically takes 3–5 business days. If you need your order more quickly, Expedited delivery via Royal Mail Tracked 24 is available, offering a 1–2 business day service.
Large or bulky items may be sent via courier at our discretion and are usually dispatched for next-day delivery. Please note that we only ship to mainland UK addresses; delivery to non-mainland locations, including the Highlands & Islands, may not be available for large or heavy items. If your address falls into one of these areas and you wish to purchase such items, please contact us with your postcode and order details before placing your order. If we cannot ship to you, you are welcome to arrange your own courier for collection.
All products, unless otherwise stated, come with a standard manufacturer warranty against faulty workmanship.
If your product fails within six months of delivery, please contact us with your order reference number, a description of the issue, and clear images illustrating the fault.
Should your item require a return for further investigation, it is your responsibility to arrange and cover postage back to us.
If we are unable to repair the fault, we may offer either a replacement or a full refund.
In cases where the item is inspected and found not to be faulty, or where damage is determined not to be due to manufacturing defects, you will not be entitled to a refund or replacement. We will then either return the item to you via standard post or dispose of it at your request.
You may return any order within 14 days of delivery. As soon as you receive your items, please inspect them carefully, taking reasonable care to keep both the product and its packaging clean and undamaged. If you discover an error or defect after 14 days, we reserve the right to decline your return. If your product fails or breaks after this 14-day time window then your order may be eligible for a warranty claim, please see our warranty information for more details.
To initiate a return, please contact us via our contact form to obtain a return authorisation and the correct returns address (different from the address on your invoice). This can also be done through your 'recent orders' page on your account if you are registered with Shop. Returns sent without prior authorisation will be discarded.
Returned items must be in the same condition in which you received them: unworn or unused, with tags attached and in their original packaging. You must include either a copy of your invoice or a slip with your order reference number inside the parcel. Please be sure not to obscure your return reference number on the label.
If you refuse delivery or reject the parcel without prior notice, we will inspect the returned package and issue a refund upon receipt. Although there is no restocking fee, we will deduct the cost of the return postage label (£3.35) from your refund.
If the returned item or its packaging shows signs of use, damage, or staining, we may deduct up to 50% of the order value, or refuse the return entirely, depending on its condition. Examples include damaged tags, stained, modified or damaged packaging, or missing components.
For faulty, incorrect, or damaged items, please contact us before sending anything back so we can attempt to resolve the issue directly. If we agree that a return is necessary due to our error, we will provide you with a pre-paid return label.
Products that have been modified or damaged through customer action are not eligible for return. This includes, but is not limited to, items that have been cut, trimmed or otherwise altered (such as a tarpaulin or pond liner resized to your specifications), or any product showing damage beyond normal inspection handling.