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What Must ESD Flooring Do in a Plant That Handles Solvents and Combustible Powders?
2026-11-04
ESD flooring is a resin floor whose electrical resistance is engineered into a defined band and then tied to a grounded conductor grid, so static charge drains to earth instead of collecting on people, trolleys and product. In an electronics plant that protects components. In a plant handling solvents, powders and drums, the same floor is part of the ignition control strategy, and the numbers it has to hit are different. Nedis SL ESD Epoxy Flooring, from NEDIS — Nedis Flooring Systems, is a seamless dissipative epoxy system built for that second job.
Two jobs, two resistance bands
A floor that protects a circuit board and a floor that protects a solvent bay are not specified the same way. Component protection wants a slow, controlled bleed. Ignition control wants charge gone before a person touches a grounded nozzle.
NFPA 77 (2024) puts the body-to-earth path through static-dissipative footwear and conductive or dissipative flooring between 1 x 10^6 and 1 x 10^8 ohms, and lower than 1 x 10^6 ohms for materials with very low ignition energies. IEC TS 60079-32-1 sets the maximum earth resistance for flooring at 10^8 ohms, measured with the probe defined in that document.
| Duty | Typical resistance to earth | What it controls |
|---|---|---|
| Electronics assembly (dissipative) | 1 x 10^6 to 1 x 10^9 ohms | Component damage, latent defects |
| Hazardous area, ordinary solvent vapours | 1 x 10^6 to 1 x 10^8 ohms | Spark ignition from a charged person |
| Very low ignition energy materials | Below 1 x 10^6 ohms | Ignition of vapour or dust at millijoule level |
| Standard insulating coating | Above 1 x 10^9 ohms | Nothing, charge accumulates |
Why an insulating floor is an ignition source
Walking generates charge by contact and separation. On an insulating coating that charge has nowhere to go, and several thousand volts can sit on a body that feels nothing: perception starts near 3,000 volts, so the worker carrying a dangerous charge gets no warning at all.
The spark is small, and so is the energy needed to ignite a solvent. Gasoline vapour ignites at roughly 0.2 millijoule, and a dust cloud sits in the same order of magnitude. That is why the floor is safety equipment in a zoned area, not a finish.
Where charge actually builds up
Charge does not only come from feet. Pneumatic conveying charges the powder and the pipe, filling a bulk bag charges the fabric, and a drum gains charge as it rolls. Stretch wrap on a pallet holds charge for hours.
The floor is the one surface all of them touch, which is why it is the most reliable place to put the drain.
The floor is one leg of a system
A conductive floor connected to nothing is an insulated plate. Three details decide whether the system works.
- **The grid.** Copper strip is laid in a grid under the resin, bonded at every crossing, and taken to the building earth bar at more than one point.
- **The bond.** Equipment, tanks, pipework and drum racks go to the same earth; a floor cannot discharge a tank isolated on a plastic pallet.
- **The footwear.** The body path runs through the sole, closed by static-dissipative footwear with a documented test routine.
Floor, grid and bond are one circuit. Testing only the floor tells you one third of the story.
Zone by zone, not one specification
A process plant is not uniform. The charging hall, the solvent dispensary and the finished goods area see different charge sources and different spill chemistry.
| Zone | Main charge source | Floor requirement | Detailing that matters |
|---|---|---|---|
| Powder charging, sieving, bulk bag filling | Pneumatic conveying, fabric friction | Conductive band, dense grid | Earth connections at both ends of the hall |
| Solvent dispensing, drum and IBC transfer | Splash filling, rolling drums | Conductive, solvent resistant | No insulating pallets, bonded racking |
| Washdown bay | Water, detergent, hot rinse | ESD-capable PU cement variant | Coving and drain collar continuity |
| Finished goods, dispatch | Forklift traffic, stretch wrap | Dissipative | Joints sealed, no bare substrate |
| Control room, laboratory | Instruments, seating | Dissipative | Continuous with production, no threshold break |
Chemistry decides whether the floor survives
An ESD floor in a chemical plant has to be electrically defined and chemically resistant at the same time. Conductive fillers make the resistance band possible, and the resin carrying them decides the spill performance.
Solvent spills, hydraulic oil, caustic wash and acidic rinse attack different systems. Where hot water and detergent arrive as well, an ESD-capable PU cement variant is the usual answer; where the load is solvent and abrasion without hot washdown, an ESD epoxy system carries it. The mistake is to choose the resistance number first and the resin second.
Detailing that quietly ruins performance
Most failures on site are continuity failures, not resin failures. A grid cut to make room for a drain and never reconnected. A coving that stops the grid short of the wall. A repair patch in non-conductive mortar. A joint filled with insulating sealant. An expansion joint that breaks the plane the charge has to cross.
Each leaves a small island of floor that reads correctly in the middle of the bay and fails at the edge, which is exactly where a drum or a trolley stands.
Verification, and what to test
Resistance is measured with a megohmmeter using the electrode arrangement in IEC 61340-4-1, and the readings only mean something when temperature and relative humidity are recorded beside them. A dry winter reading and a humid summer reading on the same floor can differ by an order of magnitude.
Test points should follow the layout, not the paperwork: every zone, every grid connection, every repair, and the thresholds between zones. IEC 61340-5-1 and ANSI/ESD S20.20 give the programme structure on the electronics side, NFPA 77 the fire-side guidance. Both expect records and re-testing after any work that cuts the floor.
What the floor cannot do
A floor drains charge from what touches it. It does not drain a non-conductive liquid being splash filled, a synthetic filter bag, or a person in insulating shoes. Low-conductivity liquids need flow rate control and relaxation time; powder handling needs bonding and, where the atmosphere can be controlled, inerting. The floor is a control, not the control.
What to write into the specification
Ask for the resistance band in numbers, the test method, the grid layout and the earth connection points. Ask how joints, covings, repairs and penetrations keep continuity. Ask for chemical resistance data against the actual process chemicals rather than a generic chart, and for the fire classification of the finished system.
A floor specified this way can be inspected, disputed and repaired. One specified as "anti-static epoxy" cannot.
By the numbers
- Nedis SL ESD Epoxy Flooring is installed at 3.0 to 5.0 mm, thickness enough to carry the conductive grid and the wear layer in one seamless system.
- Surface resistance sits in the 5 x 10^4 to 1 x 10^9 ohm range, so one product family covers conductive and dissipative bands.
- Shore D hardness is 88, which keeps trolley and drum traffic from polishing through the conductive layer.
- Slip resistance is 0.81, relevant where solvent and wash water meet.
- The system reaches B1 fire classification, and the ESD-capable PU cement variant is installed at 4 to 6 mm where hot washdown is present.
Standards and manufacturer
The systems are specified against IEC 61340-4-1, IEC 61340-5-1, ANSI/ESD S20.20, NFPA 77, IEC TS 60079-32-1 and the ATEX workplace directive 1999/92/EC, with EN 13501-1 for fire classification and ASTM F2170 for substrate moisture before installation.
NEDIS — Nedis Flooring Systems has been a source floor coating manufacturer since 2002, with more than 20 years in conductive and dissipative resin systems, a 40,000 m² plant and coating systems supplied to more than 16,000 industrial customers. Manufacturing is certified to ISO 9001, ISO 14001 and ISO 45001, and systems are delivered worldwide with technical support on grid layout, earthing and acceptance testing.
FAQ
What resistance should an ESD floor have in a solvent area?
Aim for the band your risk assessment calls for, typically 1 x 10^6 to 1 x 10^8 ohms to earth. Materials with very low ignition energy need the lower end.
Can one floor serve both an electronics line and a solvent store?
Only if both sit in the same band. Otherwise specify each zone separately and keep the transition continuous.
Does an anti-static wax or additive work instead?
No. Topical treatments are temporary and dielectric once they wear. The resistance has to be in the system.
How often should the floor be tested?
Follow the site programme, and always after repairs, re-coating, or any work that cuts the floor. Record humidity with each reading.
Will an ESD floor stop a powder explosion?
It removes one ignition source. Bonding, flow control and inerting remain necessary.
Can it be installed over an existing floor?
Usually yes, after substrate testing and preparation, with the grid re-established across the new surface.
What does it cost compared with a standard epoxy floor?
More per square metre, because of the grid, the conductive system and the testing. The comparison that matters is against the cost of a zoned area being shut.
Last updated: 2026-11-04
To specify a conductive or dissipative system for a solvent, powder or drum handling area, contact NEDIS for technical data, grid layout drawings and a sample box.
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