Grommets/ Ring Rubbers

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  • Regular price R 12.00
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Grommets are used to create watertight seals for the plumbing of hydroponic systems such as NFT systems, DWC systems, Dutch Bucket systems, water reservoirs etc.

A hole is drilled and the Grommet is inserted into the hole. Piping is then pushed through the grommet which will form a watertight seal.

Product Specs

Irrigation Piping, Ring Grommet and Top Hat Grommet measurements follow below:

Grommet Sizes

Size Irrigation Piping Size Ring Grommet Size Top Hat Grommet
5mm 6mm 6mm
12mm* 12mm / 15mm * 16mm
15mm 20mm 19mm

20mm irrigation piping: –

25mm white PVC electrical conduit: 25mm Ring Grommet 

Hole Saw Sizes for Grommets**

Size Ring Grommet Hole Saw Size
Size Top Hat  Grommet Hole Saw Size
6mm 9mm drill bit 6mm 9mm drill bit (very tight fit) or 10mm drill bit
12mm 19mm 16mm 19mm
15mm 19mm 19mm 21mm
20mm 25mm
25mm 31mm  

* 12mm irrigation piping:

  • 12mm Ring Grommet fit will be a very tight fit, while a 15mm Ring Grommet’s fit could be a little loose
  • This could be countered by using an insert fitting (eg. straight connector/T-piece/elbow) inside the piping at the point where it goes through the grommet, to flare out the piping and create the waterproof seal.

** Hole Saw Sizes:

  • These hole saw sizes are for flat surfaces, not for curved surfaces.
  • A slightly smaller hole can be tried on curved surfaces to prevent possible leakage due to the curving of the grommet on the curved surface.
  • Drilling test holes and testing if seals are watertight is always advised.

Please Note:

  • It is not recommended that Petroleum Jelly is used as a lubricant. A silicon lubricant, although more expensive, is better. Olive oil can also be used.
  • If grommet is fitted and then taken out a number of times, it may stretch and warp.