Astralpool Seal Plate - CTX / E-Series MkII & XP, Nov 2020 SP40030
Astralpool Seal Plate - CTX / E-Series MkII & XP, Nov 2020 SP40030 is temporarily out of stock and will ship as soon as it's available.
Don't Guess - Ask Us!
Don't Guess - Ask Us!
Not sure if it’s the right part? Send us a message and a photo of what you’re replacing, or what you need, and we’ll help make sure you get the right part the first time.
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Delivery and Shipping Info*
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Astralpool Seal Plate - CTX / E-Series MkII & XP, Nov 2020 SP40030
Astralpool Seal Plate - CTX / E-Series MkII & XP, Nov 2020 SP40030 is temporarily out of stock and will ship as soon as it's available.
Astralpool Seal Plate - CTX / Viron / E-Series MkII & XP, Nov 2020 SP40030
This is the genuine Astralpool MkII seal plate, part number SP40030 (catalogue 40030). The seal plate sits between the wet end and the motor, carrying the mechanical seal and sealing the water chamber from the motor shaft. This is the current-style seal plate introduced from November 2020, shared across a wide range of current pumps.
- Physically Stocked, unlike most "drop-shipping" websites.
- Shipped from VIC, NSW, WA, QLD
Fits These MkII Pumps
The MkII seal plate and its matching wet end (SP40031) are shared across the current generation:
- CTX MkII — CTX 280, CTX 360C, CTX 400, CTX 500
- E-Series MkII — 140C, 170C, 230C, and E-Series pumps 11475 / 11476 / 11477 / 11478
- Viron P320 & P520 XT (Nov 2020 to June 2021 build)
- AstralPool XP pump range — 21615, 21620, 21623, 21630, 21633
Three Generations — Order the Right One
Astralpool changed the seal plate twice, alongside the wet end. The seal plate and volute must come from the same generation as your pump:
| Generation | Seal plate | Matching volute |
|---|---|---|
| Series 1 — old style, pre-Aug 2014 | 4009002 | 4007502 |
| Series 2 — Aug 2014 to 2020 | 40098 | 40097 |
| MkII — Nov 2020 onwards | SP40030 — this product | SP40031 |
If you are not sure which generation your pump is, send us a photo of the pump and its data plate and we will identify it.
Fit the Mechanical Seal at the Same Time
Whenever the seal plate comes out, the mechanical seal is disturbed. Always fit a new mechanical seal (75509) and a new seal plate o-ring (70022) with a seal plate — reusing either is the most common cause of a leak straight after the job.
Related MkII Parts
- SP40031 — volute / wet end, MkII (buy here)
- 75509 — mechanical seal, current pumps (buy here)
- 70022 — seal plate o-ring
- 78772 — seal plate to wet end bolts (x6)
- Impeller — sized to your model, see the CTX or Viron XT impeller ranges
Frequently Asked Questions
How do I know if I need the MkII seal plate?
MkII was fitted from November 2020. It covers the CTX MkII, E-Series MkII, AstralPool XP range, and the Viron P320/P520 XT of the Nov 2020 to June 2021 build, matched to the SP40031 wet end. If unsure, send us a photo of the data plate.
Does this really fit that many pumps?
Yes. Astralpool lists SP40030 across the CTX MkII, E-Series MkII, AstralPool XP and Viron XT ranges. The seal plate was standardised across the current generation.
Should I replace the mechanical seal too?
Yes, always. The seal is disturbed as soon as the plate comes off. Fit a new 75509 seal and 70022 o-ring.
Is this a genuine Astralpool part?
Yes. We are an authorised Astralpool and Fluidra dealer and warranty agent.
Manufacturer Catalogues, Diagrams & Part Numbers
Need exploded views, spare part numbers, product numbers or diagrams? See the manufacturer catalogue: Astralpool Catalogue 2026
Before ordering: confirm this part is correct for your pump. Use the catalogue above, seek professional assistance, or contact us with photos of your existing part, model details, serial numbers and any labels. As with all products, this must be diagnosed and fitted by a qualified and experienced person. This is a special-order item.
Common search terms: Astralpool SP40030, 40030 seal plate, CTX MkII seal plate, Viron XT seal plate Nov 2020, AstralPool XP seal plate, E-Series MkII seal plate.
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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SP40030