HAN-HRB1508
$2.55 NZD
All prices include GST
Big Water Tanks is an official stockist of Hansen Products — New Zealand-made True Fit threaded fittings for plumbing, irrigation, rainwater, farm and marine water systems. The Hansen Reducing Bush (HRB) screws into a larger female thread and gives you a smaller female thread, in 30 BSPT size combinations from 15 × 8mm (1/2" × 1/4") up to 100 × 80mm (4" × 3").
A reducing bush is the simplest way to step a female thread down a size — for example, from a 25mm (1") outlet on a pump, tank fitting or valve to a 15mm (1/2") hose tail or pipe fitting. The Hansen HRB has a tapered BSPT male thread on the outside (T1), a tapered BSPT female thread on the inside (T2) and a hex for a spanner. It is moulded in New Zealand from glass fibre reinforced nylon, is rated up to 16 bar at 20°C in sizes up to 50mm, and is tested to AS/NZS 4020:2018 for contact with drinking water. Below you will find the full dimension table for every size we sell, the pressure and temperature ratings, how to pick the right size, and installation tips straight from Hansen.
| Outer Thread Size | Max @ 20°C | kPa @ 20°C | @ 40°C | @ 60°C |
|---|---|---|---|---|
| 6mm – 50mm (1/8" – 2") | 16 bar | 1,600 kPa | approx. 12 bar | approx. 8 bar |
| 65mm (2 1/2") | 12 bar | 1,200 kPa | approx. 9 bar | approx. 6 bar |
| 80mm – 100mm (3" – 4") | 10 bar | 1,000 kPa | approx. 7.5 bar | approx. 5 bar |
Ratings are by the size of the larger (outer) thread. The 20°C figures are Hansen's published maximum working pressures. The 40°C and 60°C figures are read from Hansen's straight-line derating graph and are approximate. Ratings apply to fittings used with water only and installed to Hansen's specifications. Hansen tests its products for cold water use up to 60°C (140°F) and does not recommend use above 60°C.
Body: high quality glass fibre reinforced nylon (the AS/NZS 4020 test report lists the compound as Polyamide 6 Glass Fibre Reinforced — Durethan BKV 15F). Black, UV stabilised.
The Hansen EasyFit and True Fit range passed AS/NZS 4020:2018 testing (taste, appearance, growth of aquatic micro-organisms, cytotoxic activity, metals and organic compounds) at the Australian Water Quality Centre, report 356792, completed 7 March 2023.
The "Hansen True Fit" range of black plastic threaded fittings holds WRAS (Water Regulations Approval Scheme) approval number 251102715, valid 1 November 2025 to 30 November 2030. WRAS approval shows a fitting complies with the UK water fittings regulations for use on drinking water supplies.
Technical documents are published by Hansen Products (NZ) Ltd.
| Stock | Sizes 15mm–50mm are stocked in store. We hold limited stock of other sizes, and can order them in if needed. |
| Delivery | Courier nationwide. Shipping is calculated at checkout based on your location. |
| Collections | Available from 21 Akatea Road, Glendene, Auckland. |
Hansen sizes are nominal BSP sizes, not the measured diameter of the pipe or thread. A "15mm" thread is a 1/2" BSP thread, and it measures about 21mm across the outside of the male thread.
This is the female port you are screwing the bush into (e.g. a 1" pump outlet). Measure the outside of a male thread that fits it, or the inside of the female port, and match it to the table below.
This is the male fitting you want to screw into the bush (e.g. a 1/2" hose tail).
The code is simply T1 then T2 in mm: 25mm × 15mm = HRB2515.
| BSP Size | Hansen mm | Male Thread OD (approx.) | Threads per Inch |
|---|---|---|---|
| 1/4" | 8mm | 13.2mm | 19 |
| 3/8" | 10mm | 16.7mm | 19 |
| 1/2" | 15mm | 21.0mm | 14 |
| 3/4" | 20mm | 26.4mm | 14 |
| 1" | 25mm | 33.2mm | 11 |
| 1 1/4" | 32mm | 41.9mm | 11 |
| 1 1/2" | 40mm | 47.8mm | 11 |
| 2" | 50mm | 59.6mm | 11 |
| 2 1/2" | 65mm | 75.2mm | 11 |
| 3" | 80mm | 87.9mm | 11 |
| 4" | 100mm | 113.0mm | 11 |
Male thread outside diameters and threads per inch are the standard BSP (ISO 7) values, rounded. Tapered BSPT threads seal on the taper, so measure near the end of the thread.
Hansen's Threaded Fitting Handy Tips: how to apply thread tape and tighten True Fit fittings.
Full step-by-step guide: Hansen threaded fitting installation guide.
T1 is the outer (male) thread that screws into the larger port. T2 is the inner (female) thread. Both are BSPT tapered threads. Dimensions are from Hansen's HRB drawing: hex across flats (a) and overall length (b), in mm. Choose the code from the Size drop-down above.
Reading the drawing:
| Hansen Code | Metric Size | Imperial Size | Outer Thread (T1) | Inner Thread (T2) | Hex Across Flats (mm) | Length (mm) | Max Pressure @ 20°C |
|---|---|---|---|---|---|---|---|
| BSPT male | BSPT female | ||||||
| HRB1508 | 15 × 8mm | 1/2" × 1/4" | 1/2" | 1/4" | 22.0 | 23 | 16 bar |
| HRB1510 | 15 × 10mm | 1/2" × 3/8" | 1/2" | 3/8" | 22.0 | 23.5 | 16 bar |
| HRB2008 | 20 × 8mm | 3/4" × 1/4" | 3/4" | 1/4" | 29 | 25 | 16 bar |
| HRB2010 | 20 × 10mm | 3/4" × 3/8" | 3/4" | 3/8" | 29 | 25 | 16 bar |
| HRB2015 | 20 × 15mm | 3/4" × 1/2" | 3/4" | 1/2" | 29 | 25 | 16 bar |
| HRB2508 | 25 × 8mm | 1" × 1/4" | 1" | 1/4" | 35.5 | 27 | 16 bar |
| HRB2510 | 25 × 10mm | 1" × 3/8" | 1" | 3/8" | 35.5 | 27 | 16 bar |
| HRB2515 | 25 × 15mm | 1" × 1/2" | 1" | 1/2" | 35.5 | 27 | 16 bar |
| HRB2520 | 25 × 20mm | 1" × 3/4" | 1" | 3/4" | 35.5 | 27 | 16 bar |
| HRB3215 | 32 × 15mm | 1 1/4" × 1/2" | 1 1/4" | 1/2" | 43.5 | 31.5 | 16 bar |
| HRB3220 | 32 × 20mm | 1 1/4" × 3/4" | 1 1/4" | 3/4" | 43.5 | 31.5 | 16 bar |
| HRB3225 | 32 × 25mm | 1 1/4" × 1" | 1 1/4" | 1" | 43.5 | 31.2 | 16 bar |
| HRB4015 | 40 × 15mm | 1 1/2" × 1/2" | 1 1/2" | 1/2" | 50.0 | 33.5 | 16 bar |
| HRB4020 | 40 × 20mm | 1 1/2" × 3/4" | 1 1/2" | 3/4" | 50.5 | 33 | 16 bar |
| HRB4025 | 40 × 25mm | 1 1/2" × 1" | 1 1/2" | 1" | 50.5 | 33.5 | 16 bar |
| HRB4032 | 40 × 32mm | 1 1/2" × 1 1/4" | 1 1/2" | 1 1/4" | 50.5 | 33 | 16 bar |
| HRB5015 | 50 × 15mm | 2" × 1/2" | 2" | 1/2" | 61.5 | 38 | 16 bar |
| HRB5020 | 50 × 20mm | 2" × 3/4" | 2" | 3/4" | 61.5 | 38 | 16 bar |
| HRB5025 | 50 × 25mm | 2" × 1" | 2" | 1" | 61.5 | 38 | 16 bar |
| HRB5032 | 50 × 32mm | 2" × 1 1/4" | 2" | 1 1/4" | 61 | 38 | 16 bar |
| HRB5040 | 50 × 40mm | 2" × 1 1/2" | 2" | 1 1/2" | 61 | 38 | 16 bar |
| HRB6532 | 65 × 32mm | 2 1/2" × 1 1/4" | 2 1/2" | 1 1/4" | 79 | 42 | 12 bar |
| HRB6540 | 65 × 40mm | 2 1/2" × 1 1/2" | 2 1/2" | 1 1/2" | 78.5 | 42 | 12 bar |
| HRB6550 | 65 × 50mm | 2 1/2" × 2" | 2 1/2" | 2" | 78.5 | 42 | 12 bar |
| HRB8040 | 80 × 40mm | 3" × 1 1/2" | 3" | 1 1/2" | 92 | 45 | 10 bar |
| HRB8050 | 80 × 50mm | 3" × 2" | 3" | 2" | 92 | 45 | 10 bar |
| HRB8065 | 80 × 65mm | 3" × 2 1/2" | 3" | 2 1/2" | 92 | 45 | 10 bar |
| HRB10050 | 100 × 50mm | 4" × 2" | 4" | 2" | 117.5 | 51 | 10 bar |
| HRB10065 | 100 × 65mm | 4" × 2 1/2" | 4" | 2 1/2" | 117 | 51 | 10 bar |
| HRB10080 | 100 × 80mm | 4" × 3" | 4" | 3" | 117.5 | 51 | 10 bar |
Using your fittings with anything other than water? Check Hansen's chemical resistance chart for True Fit threaded fittings before you install. Pool and spa chlorine, bleach, strong acids and oxidising agents all attack the material.
View Chemical Compatibility ChartStep-by-step thread sealing and tightening, do's and don'ts, and how to pressure test a new Hansen threaded joint, with Hansen's handy tips video.
View Installation GuideYou need the Hansen HRB2515. It has a 1" (25mm) BSPT male thread on the outside, which screws into your 1" female port, and a 1/2" (15mm) BSPT female thread on the inside for your 1/2" fitting. It is 35.5mm across the hex flats and 27mm long, and it is rated to 16 bar at 20°C. The code always reads larger thread then smaller thread in mm, so 32mm to 20mm is HRB3220 and 50mm to 25mm is HRB5025.
A Hansen reducing bush is male on the outside and female on the inside. The outer BSPT male thread (T1) screws into a larger female thread, such as a pump outlet, tank fitting or valve. The inner BSPT female thread (T2) then accepts a smaller male fitting. Hansen describes the HRB as "used to reduce the size of female threads". If you need male threads on both ends, Hansen also makes reducing hex nipples.
Yes. Hansen True Fit threaded fittings are made from a raw material approved for potable (drinkable) water. The range passed AS/NZS 4020:2018 testing for products in contact with drinking water (Australian Water Quality Centre report 356792, 2023), and the True Fit range holds UK WRAS approval number 251102715, valid to 30 November 2030. Hansen notes the material is suitable for domestic water, not pool or spa water.
Yes. Hansen says to use a thread sealant on all threaded connections, even though the threads are tapered. Use either a thread sealing paste or PTFE (Teflon) tape. Hansen recommends Loctite 5331. The right sealant is non-hardening, compatible with plastic, and doesn't add slipperiness that encourages over-tightening. Wrap tape clockwise when looking at the end of the male thread, starting just back from the first thread.
Hand tight plus one to two turns, and no more. Screw the fitting in by hand until it is firm, then use a spanner or pipe grip on the hex for one to two more turns. Hansen is clear on this: do not over-tighten. Hansen's handy tips video makes the same point: the aim is a good seal, not maximum tightness.
At 20°C, Hansen rates True Fit threaded fittings at 16 bar (1,600 kPa) for sizes from 6mm to 50mm, 12 bar (1,200 kPa) for 65mm, and 10 bar (1,000 kPa) for 80mm to 100mm. The rating is set by the larger (outer) thread size. Pressure ratings fall as temperature rises. At 60°C, Hansen's graph shows about 8, 6 and 5 bar respectively. The ratings apply to water only, with the fitting installed to Hansen's specifications.
No. Hansen tests its products for cold water use up to a maximum of 60°C (140°F) and does not recommend use above 60°C, because plastic expands as temperature rises. Fittings that fail above 60°C are not covered by Hansen's Limited Lifetime Warranty — so do not use them on hot water lines that run above 60°C.
Hansen reducing bushes are BSPT x BSPT, meaning British Standard Pipe tapered threads on both the outer male and inner female threads. This is the standard pipe thread used in New Zealand and Australia. BSP and NPT threads have different thread angles and pitches in most sizes, so don't assume an NPT thread will seal in a BSPT fitting.
No. Hansen's mm sizes are nominal BSP thread sizes, not pipe outside diameters. 15mm is a 1/2" BSP thread, and its male thread measures about 21mm across. Likewise, 20mm is 3/4" (about 26.4mm), 25mm is 1" (about 33.2mm) and 50mm is 2" (about 59.6mm). Match the thread, not the pipe, then use the correct pipe fitting for your pipe type.
Yes. Hansen says True Fit fittings can be used with metal fittings. Use a plastic-compatible thread sealant, tighten to hand tight plus one to two turns, and make sure all pipework is properly supported so the nylon fitting is not carrying the weight of metal pipe or valves.
No. Hansen advises that the high chlorine concentrations in pool and spa water will attack the fitting material. True Fit fittings are only suitable for domestic water, and fittings used on pools or spas are not covered by Hansen's Limited Lifetime Warranty. Their chemical resistance chart also rates bleach, halogens and oxidising agents as bad. See our Hansen chemical compatibility page.
Hansen True Fit fittings are suitable for use above or below ground. However, Hansen does not recommend using any True Fit fittings under driveways, paths or foundations. All pipework must be adequately supported.