Zodiac Spider Gasket 50mm Top Mount Multiport Valve - Titan ZT700B, ZT800, ZT900 - W02311003
Zodiac Spider Gasket 50mm Top Mount Multiport Valve - Titan ZT700B, ZT800, ZT900 - W02311003 is temporarily out of stock and will ship as soon as it's available.
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Warranty Information
Warranty Information
Zodiac Spider Gasket 50mm Top Mount Multiport Valve - Titan ZT700B,...
Zodiac Spider Gasket 50mm Top Mount Multiport Valve - Titan ZT700B, ZT800, ZT900 - W02311003 is temporarily out of stock and will ship as soon as it's available.
Zodiac Spider Gasket 50mm Top Mount Multiport Valve W02311003
Genuine Zodiac replacement spider gasket for the 50mm (2") six-way top mount multiport valve fitted to Titan Series fibreglass sand filters. One gasket is used per valve. It is item 11 in the multiport valve replacement parts list in the Zodiac Titan manual, and on this valve it is supplied on its own, not bonded to the valve rotor.
- Physically Stocked, unlike most "drop-shipping" websites.
- Shipped from VIC, NSW, WA, QLD
When This Part Needs Replacing
The spider gasket seals between the valve rotor and the valve body, and is what keeps each valve position separated from the next. As it hardens, flattens or tears, water bypasses between the ports. The usual signs are:
- Water running continuously out the backwash or waste line while the valve is set to Filter
- Pool water level dropping while the pump runs
- Poor backwash or rinse performance, or the valve not holding a position cleanly
The valve rotor o-rings (W02011022, two required) and the valve lid o-ring (W02011006) age alongside the gasket and are worth replacing at the same time.
What It Fits
| Equipment | Detail |
|---|---|
| Zodiac Titan Series sand filters | ZT700B, ZT800, ZT900 |
| Zodiac 50mm top mount multiport valve | W88280306, six-way, item 11 on the valve parts list |
| Emaux V-Series sand filters | V700B, V800, V900 (bolt type, top mount) |
| Emaux MPV02 multiport valve | 2.0" six-way top mount, key 11 |
| Emaux MPV04 multiport valve | 2.0" side mount, key 18, used on S-Series and MAX side mount filters |
| Reltech 50mm multiport valves | Same valve, sold under the Reltech brand as W02311003 |
Equivalent Part Numbers
The Zodiac Titan is the Emaux V-Series filter supplied under the Zodiac brand, and Zodiac part numbers are the Emaux numbers with a leading "W" added.
| Brand | Part Number |
|---|---|
| Zodiac | W02311003 |
| Emaux | 02311003 (also shown as 2311003) |
| Reltech | W02311003 |
| Other labelling | WWDG50MPV, MPV02 spider gasket, 50mm MPV diverter gasket |
Does Not Fit
- 40mm (1.5") Zodiac and Emaux top mount valves, which use the smaller W02311002 gasket
- Astralpool and Hurlcon multiport valves, which use their own gaskets: 75929 for 50mm and 75916 for 40mm
- Turn-lock lid multiport valves, where the gasket is supplied bonded to the rotor as one assembly
Other Parts for This Filter and Valve
Every other part for the Titan filter and its 50mm top mount valve, with the exploded diagram numbering, is listed on the Zodiac Titan and Emaux V-Series sand filter and multiport valve parts page.
Manufacturer Catalogues, Diagrams & Part Numbers
Need exploded views, spare part numbers, product numbers, diagrams, or more product information? See the manufacturer catalogues: Astralpool Catalogue 2026 | Zodiac Catalogue 2026
Important Before Ordering: Please ensure you order correctly. Confirm this product is suitable before ordering. Use the catalogues above, seek professional assistance, or contact us with photos of your existing part, model details, serial numbers, and any labels.
As with all products, these must be diagnosed and fitted by a qualified and experienced person. This is a special-order item.
To the layperson, plumbing sizes and their names can be confusing due to the nominal sizes and naming conventions used.
This is not something we made up. Plumbers and manufacturers have used nominal (meaning ‘by name only’) sizing for decades.
Simply put, in plumbing, named sizes are often not the actual measurements of the pipe, fitting, or part. A PVC pipe called “50mm” or “2"” does not measure 50 mm anywhere. Instead, it follows nominal sizing, an internationally-standardised naming system.
Almost all fittings we use in the pool & spa industry use “pressure PVC” pipe & fittings. Do not confuse with “DWV” or other pipe & fittings and their names and sizes.
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 |
To reiterate, these are nominal sizes and are designed to fit matching fittings — not to measure 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 and other plumbing areas 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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W02311003
