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Green Drain™ · 3.5″/4″ · 88–102 mm

Green Drain™ 3.5″/4″
Combo seal.

3.5 / 4 inches · 88–102 mm grate inner diameter

Second combo variant — fits both 3.5″ and 4″ gullies. Optimal for large facilities where gully sizes are mixed between 90 and 100 mm.

Pipe size
3.5″/4″ · 88–102 mm
Flow rate
323.17 L/min
Install time
30 seconds
€56.99 · VAT included
Price excluding VAT: €45.59
In stock · dispatched from our Croatian warehouse · 5–8 working days to Ireland
Need a formal quote, volume pricing, or delivery to several sites?Request a quote →
cUPC IAPMOASSE 1072-2020In stock in Zagreb

Inspect the seal after 6 to 12 months in service to confirm the silicone is intact and sealing properly. Replace only as needed — drains in constant use wear sooner, lightly used ones often last a year or more.

Price includes VAT. Delivery to Ireland is calculated in the cart from weight and item count, and shown before you pay. Businesses with a valid VIES VAT number are invoiced without VAT under the reverse charge.

VAT-exempt intra-EU invoice (Art. 138)For businesses
HACCP Int. RG-05NSF/ANSI 2SGS QDF25-0049810-01CE ETA-18/0536EU MDR 2017/745 (Class I)ASSE 1072-2020CSA B79-2008cUPC IAPMO 9301

Technical specification

Green Drain™ 3.5″/4″ (GD-3.5/4) — silicone seal with ABS frame. All manufacturer specifications.

Size3.5″/4″ (88–102 mm)
Seal materialMedical silicone
Frame materialUV and chemical resistant ABS
Built-in unit height50 mm
Maximum flow323.17 L/min
Temperature range−40 °C to +100 °C
Seal lifeAbout 5 years in normal use
ASSE 1072 cycles2,500+ test cycles
Aerosol Blockage (SGS)99.9 % MS2 surrogate
Packaging1 piece in a box + instructions
Weight110 g
Product codeGD-3.5/4
GTIN00860008089816
Pressure resistance>400 Pa in both directions (DTI 957187)
SGS test reportQDF25-0049810-01
Medical deviceEU MDR 2017/745, class I
Manufacturer SRNDK-MF-000052289
CE markingsEU MDR 2017/745 and CPR 305/2011 (ETA-18/0536)
WaterMark licenceWM-022837 · WMTS-522:2021

What is Green Drain™?

Patented one-way silicone seal that is installed in the body of an existing floor drain. Under the weight of water it opens downward, and at rest it remains hermetically sealed upward — physically blocking sewer gases, viral aerosols, and insects.

No water in the P-trap, no chemicals, no maintenance. Medical-grade silicone, proven long-lasting durability, SGS-tested to block >99.9 % of MS2 viral surrogates.

Learn more about Green Drain™ →
Green Drain™ cross-section
Technical cross-section

Where is it used?

Large facilities with mixed 3.5″/4″ gullies — one SKU covers both, reducing inventory holding.

Professional kitchens

Hot line, prep area, cold kitchen (garde manger)

Learn more →

Hotel bathrooms and wellness

Shower stalls, hammams, spa

Learn more →

Hospital shower enclosures

Standard 3″ shower gully in patient rooms

Learn more →

Sports halls

Shower enclosures for high schools, universities, and fitness centres.

Learn more →

Wine cellars

Standard cellar floor gully

Learn more →

Pest control

Mechanical barrier for fruit and drain flies

Learn more →
View all 18 industries →

Detailed sector guide with recommendations on sizing, EU certifications and the Irish regulatory framework.

Installation in 30 seconds.

No plumber needed. No tools. No cutting into existing pipes. DIY or professional installation.

Step 1 — Remove the grate
Step 1
Take off the grate.
Remove the existing grate or strainer from the drain.
Step 2 — Insert Green Drain
Step 2
Insert Green Drain™
Lower the silicone seal 5–10 cm into the drain body.
Step 3 — Press
Step 3
Press into place
Silicone ribs adjust to the diameter. It works immediately.
Step 4 — Put the grate back
Step 4
Refit the grate
Done. Thirty seconds' work, lasting protection.

Questions about this size.

What customers ask about the GD-3.5/4.

GD-3.5/4 silicone ribs are expanding — they compress and expand inward until they fill the gully. They seal at both the smaller (3.5″) and the larger (4″) diameter.
No. The GD-3.5/4 passes 323.17 L/min — more than a normal load delivers at once. The seal opens downward under the weight of the water.
Wet cloth for regular floor cleaning. The seal remains in the drain; the grate is removed from above it. Visual inspection once a year.
Yes. Silicone is resistant to sodium hypochlorite up to 5 %, quaternary amines, isopropanol, and ethanol at standard food service and hospital concentrations.
Yes. Green Flow d.o.o. is the authorised distributor of Green Drain™ for Ireland and Northern Ireland. Each unit comes with the manufacturer's original QR code and serial number.

Not sure if 3.5″/4″ is your size?

Send us a photo of your gully and our technical support will recommend the exact size — free of charge, the same business day.

GD 3.5–4″ fits a drain body with an internal diameter of 88–102 mm. If your measurement falls in that range, this is your size.
1
Lift the grate

Take out the existing grate or strainer. Underneath is the drain body — the pipe the seal drops into.

2
Measure the internal diameter

Measure the pipe opening, not the grate. The grate is always wider, and that is the single most common reason people order the wrong size.

3
Match it to a range

Find the size whose range your measurement falls into. If you are between two, take the smaller one — the silicone ribs expand.

Where to measure

Measure the pipe. Not the grate, not the bowl.

Not the grateNot the grateThe grate is wider than the pipe beneath it.
Not the bowlNot the bowlThe bowl is not the measurement either.
Only the pipeOnly the pipeThe internal diameter of the pipe below the bowl.

Measure wall to wall, straight through the centre of the opening.

Fits round and square drains, floor sinks and trench drains.
Round
Round
Square
Square
Floor sink
Floor sink
Trench
Trench

No tape measure to hand? A strip of paper works: wrap it around the opening, mark where it overlaps, measure that length and divide by 3.14. And if you still get the size wrong, there is a 14-day return — send it back and we swap it, no questions.

Send photo → All sizes

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