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Rubber bulkhead seal 25 or 48 mm
Regular price
$2.00
Regular price
Sale price
$2.00
Unit price
/
per
| Modèle | Price | Price per unit | vs Joint plat EPDM 3/4, lot de 10 |
|---|---|---|---|
| Joint plat EPDM 3/4, lot de 10 | $10.00 | $1.00 | — |
| Joint plat EPDM 3/4, lot de 25 | $18.00 | $0.72 | −28 % |
$0.66 × 3 with no fees
Klarna.
These rubber bulkhead fittings, also known as grommets, provide a watertight seal where a pipe passes through the wall of a reservoir or grow bed. The 25 mm model fits a 3 mm wall, and the 48 mm model fits a 2 mm or 5 mm wall depending on its groove.
A reducer brings the 25 mm opening down to 12.5 mm for a smaller pipe.
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The summary
- What you receive: a fitting of the chosen model — a 25 or 48 mm bulkhead fitting, or a reducer from 25 to 12.5 mm.
- Choosing: select based on the pipe diameter and the thickness of the wall to be passed through.
- The hole: 39 mm for the 25 mm bulkhead fitting; for the 48 mm fitting, drill to the diameter of the base of its groove.
- Fitting: hand-tight, with the seal wetted, no nut or adhesive required.
Bulkhead fittings for passing a pipe through a reservoir wall, with no nut or adhesive required
Passing a tube through the wall of a bucket or reservoir without leaks usually requires a bulkhead fitting, rigid and bulky. A wall grommet does the same job with a single flexible part. It sits in a hole drilled through the wall, held in place by a groove that grips the edge of the hole; the tube is then pushed through the centre, compressing the grommet against the wall. The result is a watertight through-wall connection that can be dismantled by hand.
25 mm, 3 mm wall thickness
39 mm hole, pipe with a 25 mm outer diameter.
Reduction 25 to 12,5 mm
Fits into the 25 mm seal for a 12.5 mm tube.
48 mm, 2 mm wall thickness
Narrow rubber grommet, for a thin wall.
48 mm, 5 mm wall thickness
Wide groove, in thermoplastic elastomer, for a thick-walled fitting.
📏 Choosing the right model
Two measurements determine the correct model. The first is the outer diameter of the pipe that must pass through: 25 mm or approximately 48 mm. The second is the wall thickness, as the seal groove must match that thickness to grip the edge of the hole without play. A groove that is too wide allows the seal to shift and leak; one that is too narrow prevents it from seating properly. You should therefore measure the wall with a calliper before choosing between the narrow 2 mm groove and the wide 5 mm groove.
Fitting a water-level indicator on a pot
In the hydroponic pot with reservoir, the 25 mm seal and its reducer hold the level tube that indicates the solution height. The same assembly can be fitted to a bucket or tank of your choice to add a transparent level indicator, visible without lifting the lid.
Drilling to the right diameter, burr-free
An oversized hole will not grip the seal; a chipped hole will cut through it and cause a slow leak. Use a hole saw, 39 mm for the 25 mm fitting, or the root diameter of the groove as measured with a vernier calliper for the 48 mm fitting, on a flat wall, then deburr the edge with a craft knife. Run a plain water test overnight before filling with nutrient solution.
Assembly is done by hand. Wet the seal with water or a water-based lubricant, pinch it to push it into the hole, then check that the groove sits snugly all the way around the edge. The tube is then pushed into the centre with a twisting motion, which compresses the rubber against the wall. For a 12.5 mm tube, first insert the reducer into the 25 mm seal, then push the tube into the reducer.
Take a 20-litre bucket whose level you want to monitor. Drill a 39 mm hole 3 cm from the base, fit the 25 mm seal followed by the reducer, and push in an elbow connected to a 12.5 mm transparent tube, running vertically up the side of the bucket. The solution level is then visible at any time.
🧪 Rubber and elastomer
The 25 mm seals, the reducer, and the narrow-groove 48 mm seal are made from black rubber; the wide-groove 48 mm seal is made from thermoplastic elastomer. Both materials remain flexible in water and withstand standard nutrient solutions. Check them each time you clean the reservoir, and replace them as soon as they harden or crack, something that tends to happen most when they are exposed to light.
🔧 Replacing a worn seal
A weeping seal can be replaced in a few minutes. Drain the tank below the level of the hole, remove the pipe then the seal, clean the edge of the hole, and fit the new seal wet. To chain several pots fitted with these bulkhead connectors, the dual-channel branch tee carries both the supply and return of the solution through a single fitting, and the soilless system maintenance guide covers the leak checks to carry out.
Technical specifications
25 mm bulkhead fitting
- Wall
- 3 mm
- Drilling
- 39 mm
- Material
- Rubber, black
- Reduction
- Towards 12.5 mmSold separately, with this gasket only
48 mm bulkhead fitting
- Narrow throat
- Wall of 2 mmRubber, black
- Wide bore
- Wall of 5 mmThermoplastic elastomer
Manufacturing
- 25 mm, reducer, 48 mm narrow
- India
- 48 mm wide-bore
- Belgique
To budget for separately
- Self-watering pot
- The 15 or 45 L hydroponic pot
- Pipe
- Rigid tube, 25 or 12.5 mm outer diameter
2 further specifications are available in the detailed view.
In the box
- 1 seal for the chosen model
Diameters, wall thicknesses, drillings, materials and origins checked on 02/10/2026 against the distributor's product sheets and 2026 price list.
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Seal dispatched by tracked parcel from France. Exact shipping costs and final delivery times are displayed at checkout once your address has been entered. Outside the European Union, import duties and taxes are the responsibility of the recipient.
Frequently asked questions
6 questions
6 key questions
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