Testing established that certain solutions at certain concentrations could ignite and contribute to a fire.

That is the opposite of what the system exists to do.

Permitted formulations, maximum concentrations and listing requirements were tightened.

In some jurisdictions existing systems had to be tested, diluted or replaced.

Listed antifreeze solutions formulated for sprinkler use replaced generic glycol.

The details differ between markets, which is why current local requirements govern rather than previous practice.

Not necessarily - and the fact that it has been in place without incident is not evidence that it is.

A loop installed decades ago may not comply with current requirements.

Established practice is a poor guide in this specific area because the rules changed.

Some regimes required existing installations to be assessed within a stated period.

The solution type and concentration both need establishing, which means testing.

This should be settled against the current local standard rather than assumed.

Too weak and it freezes; too strong and it may fall outside the listed limits.

A frozen loop splits pipework and disables the system it was protecting.

An over-concentrated solution raises the concern that prompted the restrictions.

Solutions are tested by specific gravity or refractive index rather than by assumption.

Testing is a scheduled task, since concentration changes with topping up and leakage.

Records of the solution type and measured concentration form part of the system documentation.

With a refractometer or hydrometer on a sample drawn from the loop.

Both are quick and inexpensive, which makes routine testing practical.

Sampling has to be from a point representative of the loop rather than from the fill connection.

Results are compared against the listed range for that specific solution.

A loop that has been topped up with water will read low.

How often to test, and what to write down, comes from the jurisdiction.

It must not be able to, and backflow prevention is part of the installation.

Antifreeze loops are connected to a system fed from a water supply.

The solution must not be able to flow back into potable water.

Backflow prevention arrangements are subject to their own regulation, separate from fire protection rules.

Requirements differ between markets and can be more restrictive than the fire standard.

This is one of the reasons antifreeze loops have become less popular than alternatives.

Dry sprinklers, a dry pipe system, or heating the space - and for a small area dry sprinklers are usually simplest.

A dry sprinkler extends a wet system into a cold area with water held at the warm end.

That protects a canopy or a loading bay without a separate system.

A full dry pipe system suits a wholly unheated space.

Heating the space removes the problem entirely where that is practical.

Which is appropriate depends on the size of the cold area and the cost of each option.

The solution type, its listing, the concentration and the test history.

Knowing which solution is in the system is the starting point for any assessment.

Listing documentation demonstrates it is approved for sprinkler use.

Concentration records show the loop has been maintained rather than merely filled.

The extent of the loop should be recorded, since it is often a small part of a larger system.

Signage at the riser identifying antifreeze loops is required in some regimes and is useful in all.