Cleanroom and Pharma-Adjacent PU Floors: Seamless and Low Particle

Cleanroom flooring is judged on four things a warehouse floor never faces. What it releases into the air, how it behaves at the wall, how it holds up under trolleys and what evidence exists that it performs as claimed all decide the grade.

The chemistry is familiar. The discipline around it is not, because a floor in a classified area is part of a validated environment rather than a surface to be walked on.

This article sets out what those three demands mean in practice, how static control is specified, and what documentation a client should hold at handover.

What a cleanroom actually demands of a floor

A cleanroom floor has to be non-shedding, cleanable, seamless and mechanically sound, and polyurethane cleanroom flooring is the usual base for all four because it cures to a dense, joint-free film that can be carried up the wall.

Those four requirements are ordinary; the standard they are held to is not.

A particle shedding from an open edge is invisible until a particle count is taken, which is why the count should be taken twice: once at rest and once with the room in operation.

The floor is also part of the airflow path. Air returns at low level in most designs, so anything released at floor level is carried into the return and into the room.

That is why particle shedding matters more at the floor than at the wall. The floor is the largest horizontal surface in the room and the one with the most contact.

It is also the surface that receives the most mechanical abuse: trolleys, shoe covers, cleaning machines and dropped items.

A floor specified only on chemical resistance will meet the wrong requirement. The specification needs to name release, cleanability and static behaviour together.

Particles, and where they come from

Cleanroom flooring also has to hold its finish through years of cleaning. A film that chalks will fail a cleanroom class test even if it passed the day it was laid, because chalking is release.

A cured resin film does not shed in the way a textile or a porous coating does. What it does release comes from wear, from damage and from poor detailing.

The main sources are abrasion at doorways, chipped edges at equipment feet, and dust trapped in an unsealed joint or an open skirting top.

That makes particle shedding a detailing problem more than a formulation problem. A perfectly good product installed with an open edge performs badly.

Where a cleanroom class of ISO 7 or better is required, the floor should be seamless, fully bonded, and free of any detail that can trap and release dust.

Coatings that chalk under cleaning are unsuitable regardless of their particle count in a laboratory test. Chalking is shedding with a different name.

Ask for a test report on a cured sample and read the method. A number quoted without a method and a grade cannot be compared with another supplier.

The wall junction and why skirting decides the grade

In a cleanroom the floor-to-wall junction is the most inspected detail in the room, because it is where cleaning is hardest and where contamination accumulates.

A coved skirting of 50 to 75 mm radius removes the corner and lets a mop or a wipe reach the whole surface in one pass. The healthcare version of this detail, and the height a ward expects, is set out in hospital PU flooring.

The top edge must be capped and sealed. An open top edge is a shelf, and on a shelf there is dust that no cleaning regime reaches.

Cleanroom flooring brought up the wall as a coved skirting also protects the base of a panel system from trolley damage, which is where partitions are most often struck.

Where a wall is a stud partition, the skirting should be formed before the wall lining goes on, so the two systems meet cleanly rather than being retrofitted.

A coved skirting in the same material as the floor is preferable to a separate profile. A separate profile introduces a joint, and a joint is a gap.

Inspect the junction with a torch held at a low angle. It shows gaps that a direct view hides, and it takes ten minutes on a whole suite.

Static control, and where it is genuinely needed

A static dissipative floor is specified where a discharge could damage a product or ignite a solvent. That is a narrower requirement than the market suggests.

In a classified area the earth path is part of the building services, so the floor contractor and the electrical contractor have to agree who tests it, and the answer should be written down.

The property is measured as resistance to earth, and the useful band for a dissipative floor is between 10^6 and 10^9 ohms, with conductive floors below that.

A dissipative floor only works if it is earthed. Copper tape or a conductive primer connects the film to the building earth, and the connection is tested, not assumed.

An air change rate above 40 per hour also dries a wet floor faster, which shortens the cure window and can trap solvent if the floor is laid while the system is running.

Where a client asks for a static dissipative floor without a specific reason, ask what would be damaged or ignited. The answer often shows that ordinary antistatic cleaning is enough.

Where the requirement is real, test the resistance at multiple points after installation and record the values with their locations on a plan.

Carbon-loaded systems are darker and less decorative than standard colours. That is a material fact, not a styling choice, and it should be shown to the client before the order.

Wipe-down, detergents and the film

A cleanroom is cleaned with detergents chosen for residue rather than for grease removal, and those detergents are usually milder than a food plant caustic.

Cleanroom flooring specified for a classified area should therefore be tested with the actual detergent, on the installed floor, before the room is released for use.

The risk is not chemical attack but residue. A film that holds a detergent residue becomes a source of particles when it dries.

A wipe-down routine works best on a dense, closed surface with no texture. That is the opposite of the textured finish specified for slip resistance.

Where both are required, put the texture in the circulation route and keep the critical zones smooth. A single finish across a suite always compromises one requirement.

Ask for the cleaning agents before specifying, and check the residue behaviour rather than the pH alone. An alkaline detergent that rinses clear is better than a neutral one that leaves a film.

Where a wipe-down is done with alcohol, confirm the film resists it at the concentration used. Repeated solvent wiping dulls a film faster than any detergent.

Airflow, returns and the floor’s part in it

Most cleanrooms return air at low level through wall grilles or a raised floor. A solid floor with wall returns makes the floor a surface the air sweeps across.

An air change rate of 20 to 60 per hour in a Grade C or ISO 7 room moves a large volume of air past the floor every hour, so anything released there is distributed quickly.

That is the argument for a seamless floor with sealed details rather than a tiled one. Grout lines and open joints release dust continuously and cannot be cleaned effectively.

Where the air change rate is high and the room is small, even a small release becomes a measurable particle count within minutes.

Commissioning should include a particle count with the floor in place and the room at rest, then again in operation. The difference between the two is the number that matters.

Keep both sets of results. They are the baseline for every later investigation into a particle excursion.

Validation and the evidence a client should hold

A validation protocol has to name the tests, the values and the locations rather than refer to the specification, and it has to name the wipe-down method and the detergent used. A shorter protocol is acceptable for a small suite if it still does that.

A validation protocol for a floor is usually part of a wider qualification of the room, and the floor contributes three things: installation records, surface tests and cleaning validation records.

The record should also name the earth test points where a dissipative floor is installed, because a value without a location cannot be retested in the same place.

The installation record should include batch numbers, thickness readings, joint details and photographs of every cove and penetration.

A validation protocol that relies on a laboratory report alone is weaker than one that includes a measurement taken in the finished room with the air system running.

Surface tests include particle release where required, resistance to earth for a dissipative floor, and adhesion on a sample basis.

Cleaning validation shows that the specified detergent and method bring the surface to the required condition, and it is done on the installed floor rather than on a sample.

That document is also what a new quality manager reads first when they inherit a suite, and a clear one saves weeks of uncertainty about what the floor can do.

A validation protocol that names the tests, the acceptance values and the locations is a document a client can defend in an audit. One that says the floor was installed to specification is not.

Hold the file in the room’s qualification pack. When a later change is made to the room, that file is the reference for what the floor originally achieved.

Where cleanroom floors fail

The first failure is an open skirting top, which becomes a dust shelf and a finding in every audit thereafter.

The second is an unearthed dissipative floor. The film has the right resistance and the building earth does not reach it, so the property is theoretical.

The third is a textured finish in a critical zone, chosen for slip resistance and abandoned by the cleaning team because it cannot be wiped clean.

The fourth is a repair in a different material. A patch that cures to a different gloss reads as contamination under inspection lighting.

Table 1: Four cleanroom floor failures and their cause.

Table 2: What to specify by room type.

Table 3: Tests and what each proves.

Figure 1: the coved skirting where the resin meets the panel wall.

Figure 2: a surface meter taking an earth reading on the finished floor.

Specifying a cleanroom floor

Write the room grade, the finish, the cove height, the static requirement and the evidence. Five lines, each measurable.

Cleanroom flooring at 3 to 4 mm with a smooth sealed finish, a 75 mm capped cove, a tested earth path where required, and a handover file with records for each. A screed versus coating decision for an industrial polyurethane floor coating is settled by the cove detail before the build is priced.

State the cleaning agents and the method, because a floor validated with one detergent is not validated with another.

Require the contractor to retain a sample of the installed material and the batch number, so that a repair in year three matches.

Where a cleanroom class is upgraded later, the floor is often the constraint. Building in a margin at the start is cheaper than lifting a sound floor.

Add a commissioning test with the room at rest and again in operation. The second result is the one a client will be judged on.

Maintenance and the long term

Cleanroom flooring in a classified area is also the surface most likely to be damaged by a trolley, so the maintenance plan should include a repair allowance rather than a reaction.

A cleanroom floor is maintained by cleaning and inspected by audit. Both are easier with a floor that was documented at handover.

A classified area that changes use, from storage to packing for example, may need a different finish in a zone that was previously unclassified, and the floor plan is the document that shows where the change falls.

Keep a plan with the cove locations, the earth test points and the batch numbers. A repair that follows the plan matches; a repair that does not becomes visible.

Re-test the earth path annually where a static dissipative floor is installed. A connection that has corroded reads as a failed floor when the floor is fine.

Schedule a surface review every two years. Dull patches in a doorway are the first sign of wear, and a local recoat at that stage is a small job.

Where a room is decommissioned, the floor record is part of the handover to the next occupier. It costs nothing to keep and it answers the first question a new owner asks.

Perguntas frequentes

What floor is used in a cleanroom?

A seamless resin floor, usually polyurethane or epoxy, with a capped coved skirting and no joints in the critical area.

Does a PU floor shed particles?

A cured film releases very little. Most release comes from wear, damage and open details rather than from the material itself.

When is a static dissipative floor needed?

Only where a spark would damage the product or ignite a solvent, and only if the earth path is tested afterwards.

How high should cleanroom skirting be?

A 50 to 75 mm radius is typical, formed in the floor material and capped at the top edge.

Can a cleanroom floor be repaired?

Yes, if the same material and batch are retained. A patch in a different product shows under inspection lighting.

What documentation should be handed over?

Installation records, thickness readings, earth test results, cleaning validation and photographs of every cove and penetration.

Why do cleanroom floors fail audits?

Usually an open skirting top, an unsealed penetration or a repair that does not match. All three are detailing failures.

Por que razão as fábricas de produtos alimentares trabalham com a Kaida Paint

Kaida Paint supplies cleanroom flooring systems for classified rooms, with the cove, the earth path and the documentation treated as part of the product. Send the room grade, the cleaning agents and the static requirement, and we will return a specification with the tests and the handover pack the qualification will ask for.