50mm & 40mm Astralpool & Hurlcon Pump, Heater, Chlorinator Barrel Union Nuts & Tails - Combo
50mm & 40mm Astralpool & Hurlcon Pump, Heater, Chlorinator Barrel Union Nuts & Tails - Combo is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Genuine AstralPool 40mm / 50mm Plumbing Barrel Union Set (Nut, Tail & O-Ring) to suit a wide range of Fluidra / AstralPool / Hurlcon / Filtrite pool & spa equipment. This is one of the most common pump / filter / chlorinator barrel unions used on AstralPool & Hurlcon pool pumps, filters, chlorinators, blowers and selected gas heaters where 40mm or 50mm pressure PVC plumbing is used.
- Shipped fast Australia-wide
- Pickup available: 1/10 Industry Blvd, Carrum Downs VIC
Pipe sizes supported: 50mm pressure PVC (~61mm OD) and 40mm pressure PVC (48mm OD).
Suitable for (common examples):
- AstralPool / Hurlcon Pumps: CX, CTX, TX, E-Series, XP, XF, Viron XT
- Filters: FG, UF, QL, XC, ZX, CL, CA (50mm plumbing / 50mm MPV applications)
- Chlorinators: E-Series, VX, Viron, EQ, Halo, probe housings, solar sensors, etc.
- Blowers: SX
- Gas Heaters: ICI, Viron, MX, HiNRG (not HX or JX)
- Also suits many Davey DSF, Filtrite pumps and other compatible union applications.
Update (2026): New 40/50mm combo union tail
Fluidra have updated the union tails supplied with a range of products. Instead of separate 40mm and 50mm tails, the new design is a single dual-size tail that accepts either 40mm (48mm OD) or 50mm (~61mm OD) PVC pressure pipe. The nut, O-ring and thread remain the same, but the tail is now ABS and is longer (approx. 84mm) — often eliminating the need for additional adaptors (please check clearance/overall length on tight installs).
Solvent cement / cure time (important):
Because the tail material is now ABS, we recommend using a made-for-purpose ABS-to-PVC solvent cement for best practice and long-term reliability.
Fluidra’s Technical Bulletin #MB181225 (18/12/2025) outlines the updated tail design and installation notes, including a minimum 20 minute cure time before pressure/functional testing.
In the package:
- 1 × Union Nut
- 1 × Union O-Ring
- 1 × 40mm/50mm Combo Union Tail (ABS)
Fits (general guide):
- AstralPool / Hurlcon chlorinators (most models)
- AstralPool / Hurlcon pumps (CX, CTX, TX, E-Series, XP, XF, Viron XT)
- Gas heaters: ICI, MX, Viron, HiNRG (not HX or JX)
- Most AstralPool / Hurlcon 50mm sand filter plumbing (not 40mm multiport valve applications)
- AstralPool / Hurlcon cartridge filters: ZX, QX, CL
Tip: If you’re unsure which union you need, send us a photo of your pump/filter/heater label and the existing union, plus a quick pipe measurement (OD), and we’ll help match it.
In plumbing, named sizes are not the actual measurements. A pipe called “50mm” or “2"” does not measure 50 mm across. Instead, it follows nominal sizing, an internationally-standardised naming system.
Use the Outside Diameter (OD) to check your pipe against fittings. Below is a quick reference for common spa & pool pipe sizes:
| Imperial Name | Metric Name | Pipe Diameter (OD) |
|---|---|---|
| 1" | 25 mm | ~33.4–33.7 mm |
| 1.5" | 40 mm | ~48.1–48.4 mm |
| 2" | 50 mm | ~60.2–60.5 mm |
| 2.5" | 65 mm | ~75.2–75.5 mm |
These are nominal sizes and are designed to fit matching fittings — not to measure exactly what their name suggests.
Understanding Plumbing Sizes & Nominal Measurements
Plumbing sizes can be confusing. PVC and many other pipe systems use nominal sizes—the size is a name, not the exact measured dimension. This convention is used across most pool and spa systems so that pipes and fittings remain compatible.
Why pipe sizes don’t match the measurements
The Nominal Pipe Size (NPS) system standardises pipe dimensions so that pipes, fittings, valves, and accessories interoperate. Plumbers work with these nominal names every day, but DIYers can be tripped up if they try to match by a tape-measure alone.
How to Measure Pipe Correctly
-
Pipe size is identified by:
- The pipe’s Outside Diameter (OD).
- The fitting’s Inside Diameter (ID) (socket opening).
- Pipe Class / Schedule (e.g., Class 9, 12, 18 or Sch 40) relates to wall thickness and therefore the Internal Diameter (ID) and pressure rating.
- The outside diameter of a fitting is not useful (wall thickness varies by manufacturer).
PVC Pressure Pipe AS/NZ 1477 Dimensions1:
Common nominal sizes with typical outside diameters and indicative inside diameters by class.
| Imperial Name | Metric Name | Outside Diameter (OD) | Class 9 IDº | Class 12 IDº | Class 18 IDº |
|---|---|---|---|---|---|
| 1/2" | 15 mm | ~21.2–21.5 mm | 18.3 mm | 17.8 mm | |
| 3/4" | 20 mm | ~26.6–26.9 mm | 23.7 mm | 22.4 mm | |
| 1" | 25 mm | ~33.4–33.7 mm | 30.5 mm | 29.8 mm | 28.1 mm |
| 32 mm | ~42.1–42.4 mm | 38.5 mm | 37.5 mm | 35.4 mm | |
| 1.5" | 40 mm | ~48.1–48.4 mm | 45.2 mm | 44.1 mm | 42.8 mm |
| 2" | 50 mm | ~60.2–60.5 mm | 55.2 mm | 53.7 mm | 50.5 mm |
| 65 mm | ~75.2–75.5 mm | 68.9 mm | 67.0 mm | 63.2 mm | |
| 2.5" | ~73 mm |
- º Internal diameters vary slightly by manufacturer and class.
- 1 Not all pool/spa fittings match these dimensions exactly. Some do not follow Australian or international standards. Chinese spas may use proprietary fittings.
Hose & Tube Dimensions
Common flexible hose sizes used in pool/spa systems (approximate IDs).
| Imperial Name | Metric Name | Inside Diameter (ID) |
|---|---|---|
| 3/8" | 9–10 mm | ~9 mm |
| 3/4" | 19 mm | ~19 mm |
BSP – British Standard Pipe Thread Sizes
BSP thread names are also nominal. The thread OD will not equal the nominal name.
| BSP Thread Size Naming | Outside Diameter (mm / inch) | TPI |
|---|---|---|
| 1/16" BSP | 7.7 mm / 0.304" | 28 |
| 1/8" BSP | 9.7 mm / 0.383" | 28 |
| 1/4" BSP | 13.16 mm / 0.518" | 19 |
| 3/8" BSP | 16.66 mm / 0.656" | 19 |
| 1/2" BSP / 15 mm | 20.99 mm / 0.825" | 14 |
| 5/8" BSP | 22.99 mm / 0.902" | 14 |
| 3/4" BSP / 20 mm | 26.44 mm / 1.041" | 14 |
| 7/8" BSP | 30.20 mm / 1.189" | 14 |
| 1" BSP / 25 mm | 33.25 mm / 1.309" | 11 |
| 1-1/4" BSP | 41.91 mm / 1.650" | 11 |
| 1-1/2" BSP / 40 mm | 47.80 mm / 1.882" | 11 |
| 2" BSP / 50 mm | 59.61 mm / 2.347" | 11 |
| 2-1/4" BSP | 65.71 mm / 2.587" | 11 |
| 2-1/2" BSP | 75.18 mm / 2.960" | 11 |
| 3" BSP | 87.88 mm / 3.460" | 11 |
| 4" BSP | 113.03 mm / 4.450" | 11 |
| 5" BSP | 138.43 mm / 5.450" | 11 |
| 6" BSP | 163.83 mm / 6.450" | 11 |
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