Davey SpaQuip 50mm Barrel Union - Spapower, Silensor, Maxiflow, Nipper, Hayward
Davey SpaQuip 50mm Barrel Union - Spapower, Silensor, Maxiflow, Nipper, Hayward is backordered and will ship as soon as it is back in stock.
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Davey SpaQuip 50mm Barrel Union - Spapower, Silensor, Maxiflow, Nip...
Davey SpaQuip 50mm Barrel Union - Spapower, Silensor, Maxiflow, Nipper, Hayward is backordered and will ship as soon as it is back in stock.
Davey / SpaQuip / Hayward / Piranha 50mm Coarse-Thread Barrel Union Assembly (Nut + Tail + O-ring) - 50mm barrel union plumbing fitting with coarse threads. Supplied as a complete set: union nut + tail + 50mm O-ring. These have been coloured black, red, white.
Davey / Spa-Quip
Davey & Spa-Quip spa control systems (heater unions)
- Spa Power controllers: SP600, SP601, SP750, SP800, SP1000, SP1200, SP2000
- SpaPower 600, 601, 750, 800, 1000, 1200 control systems (heater tube unions)
Davey & Maxiflow pumps
- Silensor: SLL300, SLL400
- PowerMaster 3-phase: PM4503
- PowerMaster Variable: PM400V
- ProMaster VSD: PM400PV, PM400BV
- Power Master Eco: Power Master Eco models using the same 50mm coarse-thread union style
- Maxi-Flow pumps (50mm coarse-thread union style)
Davey chlorinators / automation
- ChloroMatic Nipper: DNP15C, DNP25C, DNP35C, DNP15CLS, DNP25CLS
- ProMatic chlorinator: 48722BSP barrel union assembly
- Lifeguard system (AU/NZ): 48722BSP barrel union assembly
Davey filters
- Commonly used where Davey equipment is plumbed with this 50mm coarse-thread union standard.
- Davey Easy Clear & Davey Crystal Clear (Easyclear / Crystalclear) - check nut measurements.
Davey / Spa Quip Associated Part Numbers: Q5114BK-SET (Q5112 + Q5114BK-10 + Q5113BK), 48722BSP, 48722, 48722b, 48722b-1, 48722bsp
Hayward
Hayward pumps
- Super Pump II
Hayward Filters
- SP0715, SP0716, S244T2C, S270T2C, S310T2C, S360T2C, S244S, S310S, S360,
- DE2420, DE3620, DE4820, DE6020, DE7220 -- valve size check: SP0715XR50 (2")
Hayward part numbers associated
- SP24X50AUUNPAK
- 20-SP50RPAUUNPK
- 20-SP50RPAUUNPAK
- SP50RPT
- UN5050 / SP50RPAUUNPAK
Piranha
- Pumps: Piranha spa jet pumps & 2-speed pumps (50mm coarse-thread union style)
Quick ID guide (avoid ordering the wrong union)
- Size: 50mm aka 2"
- Pipe sizing note: Australian/New Zealand 50mm pressure PVC pipe measures approximately ~60-61mm outside diameter (OD), so don’t size this union by OD alone.
- Thread: coarse-thread style (matches many Spa-Quip / Spa Power / Davey / Hayward / Piranha applications listed above)
- Includes: union nut + tail + 50mm O-ring
Dimensions:
- Pipe Size: 50mm Pressure PVC (nominal) with outside diameter approx ~60-61mm
- Thread Diameter: Inner: ~75mm / Outer: ~79-80mm
- Number of Threads: 4-5
- O-ring Size: ~69mm OD x ~5mm cross section. (often flatten with age). Oring listed here.
Common symptoms this part solves
- Union won’t tighten properly (stripped or cracked nut)
- Persistent drip at the union (flattened/damaged 50mm O-ring)
- Hairline cracks in the tail or union face causing leaks
- Union threads damaged from over-tightening or cross-threading
Compatibility notes
- Coarse-thread vs fine-thread: there are multiple 50mm unions in the market. This listing is for the coarse-thread style.
- Hayward DE filters: confirm you have the SP0715XR50 (2") valve if matching the DE filter models listed above.
- PowerMaster Eco: some variants use different union configurations, so match the union style on your pump if unsure.
May also be called - aka Search Terms
Spa Power 601 union, Spa Power 800 union, Spa Power 1000 union, Spa Power 1200 union, Spa Power 2000 union, SP601 union, SP800 union, SP1000 union, SP1200 union, SP2000 union, Maxiflo union, Hayward union, Piranha union, Spa-Quip union, Spa-Quip barrel union, Power Master union, WWDG PMHP Union, heater union, 50mm coarse thread union.
50mm barrel union, 50mm pump union, 50mm heater union, coarse thread union, Spa-Quip union, Spa Power union, Davey 48722B union, 48722BSP union, Q5114BK-SET union, Hayward SP0715 union, Hayward SP0716 union, Super Pump II union, SpaPro Pump Union, Maxiflow union, Piranha pump union, 2" union nut tail o-ring set, union tailpiece, union O-ring 50mm, 50mm PVC pipe OD 61mm.
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) |
|---|---|---|
| 1/2" | 15mm | ~21.2–21.5 mm |
| 3/4" | 20mm | ~26.6–26.9 mm |
| 1" | 25 mm | ~33.4–33.7 mm |
| 1.5" | 40 mm | ~48.1–48.4 mm |
| 2" | 50 mm | ~60.2–60.8 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. These are based on PVC Pressure Pipe AS/NZ 1477 Dimensions1.
- 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.
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).
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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48722BSP (Q5114BK-SET (Q5112 + Q5114BK-10 + Q5113BK))