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.
Irrigation Piping, Ring Grommet and Top Hat Grommet measurements follow below:
|Size Irrigation Piping||Size Ring Grommet||Size Top Hat Grommet|
|12mm*||12mm / 15mm *||16mm|
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 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.
- 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.