Impeller & Mechanical Seal For - Davey QB Spa Jet Booster Pumps
Impeller & Mechanical Seal For - Davey QB Spa Jet Booster Pumps - is backordered and will ship as soon as it is back in stock.
Delivery and Shipping
Delivery and Shipping
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Impeller & Mechanical Seal For Davey QB1501, QB2001, QB2002, QB2501, QB2502, QB3001, QB3002 Spa Jet Pumps. Originally were black plastic. These have been replaced by a much higher-quality beige glass-filled nylon material. We only sell the highest-grade impellers. This impeller is manufactured from premium PPO material for better wear / longer life.
Please Choose your Model Below. Uses these mechanical seals.
Impeller Sizes:
-
Davey QB1501 - 1.5HP:
Outside diameter 98mm, 13mm internal vane width, 7 vanes. -
Davey QB2001 / QB2002 - 2.0HP:
Outside diameter 107mm, 11.5mm internal vane width, 7 vanes. -
Davey QB2501 / QB2502 - 2.5HP:
Outside diameter 112mm, 13mm internal vane width, 6 vanes. -
Davey QB3001 QB3002 - 3.0HP:
118mm diameter, 11mm vane width x 7 vanes / 60.5mm throat OD / may be marked B351-21 / Previous version: Outside diameter 118mm, 12.5mm internal vane width, 6 vanes / 62mm throat OD / Often marked B358-02 (but so are other sizes)
Also listed is a mechanical seal to suit. Upgraded seals also available.
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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