Food Grade Propylene Glycol: a Guide for Breweries

In this guide

• Choosing the right glycol
• Brewery and draft cooling applications
• Mixing ratios and freeze protection
• Calculating how much to buy
• Mixing, filling and topping up
• Testing concentration
• Storage and maintenance
• Buying glycol and related equipment
• Frequently asked questions

What Is Food-Grade Propylene Glycol?

Propylene glycol, or PG, is also known as 1,2-propanediol. It mixes with water to form a heat-transfer solution with a lower freezing point than water alone. That is what lets a chiller run coolant below 32 °F without ice forming.

In the United States, propylene glycol is recognized as GRAS for specified food uses under 21 CFR 184.1666. GRAS covers propylene glycol itself. A finished coolant may also contain additives, and the complete product has to suit your equipment.

What is the difference between USP and inhibited glycol?

The fluid also has to suit the metals, seals and tubing in your loop. Do not mix different coolant products unless both the chiller manufacturer and the fluid supplier approve it.

The propylene glycol we sell is USP grade and kosher (see the supplier's Propylene Glycol USP Kosher SDS). If your installation needs the formulation or current batch documents confirmed, email sales@beveragecraft.com.

Is propylene glycol an alcohol?

Chemically, yes. Propylene glycol is a diol, a type of alcohol with two hydroxyl groups. It is different from ethanol, the alcohol in beer. In a properly functioning cooling system, the coolant remains separate from the beer.

How Is Glycol Used in Breweries and Draft Beer Systems?

How does glycol cool fermentation and brite tanks?

A brewery glycol chiller cools the solution and circulates it through tank jackets or heat exchangers. Heat moves from the beer through the steel wall into the coolant, and the warmer coolant goes back to the chiller.

Tank controllers and valves regulate coolant flow as cooling is needed. Fermentation, cold crashing and several tanks operating at once create different loads. Size the chiller for the processes, tank volumes and cooling times in your production schedule.

Try our brewery chiller sizing calculator for a starting point on cooling capacity. It doesn't tell you how much glycol to buy. That is a separate calculation, covered below.

How does glycol keep draft beer lines cold?

In a long-draw draft system, a glycol power pack circulates coolant through dedicated tubes inside an insulated beer trunk line. The glycol tubes run next to the beer lines from refrigerated storage to the tower.

In a long-draw draft system, glycol helps keep refrigerated beer cold between storage and the faucet. The kegs still need suitable refrigerated storage. Gas pressure, carbonation and line balance also affect the pour.

A glycol-cooled tower keeps the last stretch of line cold as well. Frost on a tower is not a reliable indicator of performance, because insulation, humidity and coolant temperature all affect it.

What Glycol-to-Water Ratio Should You Use?

Use the ratio in your chiller manual. The BeverageCraft BrewChill Pro, ChillPro and G30 models listed in this guide specify 40% glycol and 60% water by volume. Ratios of 30% or 35% published elsewhere may apply to other equipment and should not replace your manufacturer's specification.

40/60 describes the finished mix: 4 parts glycol to 6 parts water. It doesn't mean topping up a reservoir full of water with 40% more glycol.

The table assumes undiluted PG. If yours arrives premixed, or its strength is given by weight, the numbers change, so go by the supplier's blending instructions and test the mix once it's made. All gallons in this guide are US gallons.

How does concentration affect the freezing point?

Within the concentration range shown below, increasing the propylene glycol content lowers the freezing point. The figures below are Dow's published values for one product, DOWFROST inhibited propylene glycol heat transfer fluid. We show them as a reference. They are not the spec for the glycol BeverageCraft sells. Other formulations may have different freezing points at the same stated concentration. Use the manufacturer's chart for the exact fluid and concentration basis.

Source: Dow, DOWFROST heat transfer fluid technical data. The glycol percentages refer to the propylene glycol content of the solution, not to the finished product's additive package.

This table shows freezing-point data, not a recommended operating concentration. Dow notes that inhibitor levels require adjustment in solutions containing less than 30% glycol. Follow the fluid supplier's dilution and corrosion-protection requirements.

The chiller's displayed setpoint does not represent the coldest temperature everywhere in the circuit. Evaporator surfaces and exposed piping may be colder. Follow the freeze-protection margin specified for your equipment. If the manual does not state a requirement, confirm it with the manufacturer before selecting the concentration.

Freeze protection and burst protection are different. A mixture may begin forming ice before reaching the temperature associated with pipe rupture. A circulating chiller needs enough freeze protection to maintain coolant flow; a burst-protection rating alone is not sufficient.

Does a stronger glycol mixture cool better?

Not necessarily. Increasing glycol concentration raises viscosity and can reduce heat-transfer performance. Use the concentration required by your equipment and fluid supplier rather than adding extra glycol as a precaution.

How Much Propylene Glycol Do You Need?

Add up everything the coolant fills, not just the chiller tank:

• Reservoir: use the specified working fill level.
• Piping: include both supply and return lines.
• Tank jackets and coils: get their fluid volumes from the tank manufacturer.
• Heat exchangers and other components: include their coolant-side volume.

Approximate pure PG required = total finished coolant volume × target PG fraction. For a 40% solution, multiply by 0.40.

How much glycol does a BeverageCraft chiller reservoir require?

These are published tank sizes. The working fill level can sit a little lower, so check the manual for your exact model. A ChillPro and a BrewChill Pro with the same number in the name are different machines with different specs. Canadian versions are listed in the brewery chillers and glycol chillers categories.

How much coolant is in the lines?

Use the inside diameter of the tubing. The outside diameter gives too high a number.

Line volume in liters = π × inside diameter in millimeters² × total length in meters ÷ 4,000.

For example, two coolant tubes with a confirmed 3/8-inch inside diameter, each 100 ft long, hold approximately 4.34 L / 1.15 US gal combined. At 40% PG, this adds approximately 1.74 L / 0.46 US gal of pure PG to the reservoir calculation. A 1/2-inch inside diameter tube holds about 1.02 US gal (3.86 L) per 100 ft.

Check the glycol tube size on your trunk line or tubing before using either figure. Brewery piping is usually larger and needs its own calculation.

Swap in your own volumes, round up to whole containers and keep some spare for top-ups.

For equipment selection, see How to Size a Glycol Chiller for Your Draft Beer System or How to Size a Brewery Glycol Chiller for Fermentation and Cold Crash.

How Do You Mix, Fill and Top Up a Glycol Chiller?

1. Know your fluid and ratio. Both are in the chiller manual and on the glycol label or data sheet.
2. Use clean water. Distilled or deionized water is the usual choice, since hard tap water leaves scale and minerals behind.
3. Prepare a uniform mixture. Measure and mix in a clean container. Glycol is slightly heavier than water, so pouring the two into the reservoir separately can leave them layered. Do not dilute a ready-to-use fluid unless instructed.
4. Fill to the working level. Prime the pump and bleed air the way the manual describes, and never let the pump run dry.
5. Run it, then check again. The lines and jackets pull fluid out of the reservoir, so top up to the working level and test the concentration.

Should you top up with water or premixed coolant?

Repair a leak before topping up. If testing confirms that the remaining coolant is suitable, use compatible premixed coolant at the required concentration. Water loss through evaporation can increase the glycol concentration, so measure the mixture before deciding what to add.

Repeated top-ups without a known cause point to a possible leak that should be inspected.

How do you raise a low glycol concentration?

You don't have to drain the whole loop. Work out how much mix to drain and replace with concentrate:

Replacement volume = system volume × (target concentration − current concentration) ÷ (concentrate concentration − current concentration).

Keep every percentage on the same basis, all by volume for example. With 100% PG as the concentrate, a 20 US gal loop at 30% that should be at 40% needs:

20 × (40 − 30) ÷ (100 − 30) = approximately 2.86 US gal.

Drain that much, add the same amount of concentrate, let it circulate and test again. A purity figure given by weight can't be plugged in as a volume percentage.

How Do You Test Glycol Concentration?

A handheld refractometer is the quickest way to check concentration. Some models have a propylene glycol scale that reads freeze protection directly. Others need a conversion chart for your fluid.

1. Clean the prism and calibrate the instrument as instructed.
2. Take a representative sample from the mixed circuit.
3. Apply the sample and read the correct scale.
4. Compare the result with your fluid and equipment requirements.
5. Record the reading and retest after adjustments.

A Brix reading is not percent glycol. Brix scales are built for sugar, so you need the glycol supplier's conversion for your fluid. Take the reading at the temperature and calibration the instrument maker specifies.

A refractometer checks concentration but does not reliably assess inhibitor condition or identify contamination. Contaminants can also affect the reading. If the fluid's history or condition is uncertain, ask the supplier about laboratory testing.

How Long Does Propylene Glycol Last?

Glycol on the shelf and glycol in a running loop age differently. For sealed containers, go by the expiry or retest date on the label and batch documents, and keep the lids tight.

Once it's in the chiller, follow the maintenance schedule from the chiller and fluid makers. A simple log helps: product, fill date, test results, top-ups and service visits.

• Level and leaks: check routinely and investigate unexpected losses.
• Concentration: test after filling, servicing or dilution, and at the required maintenance intervals.
• Fluid condition: investigate unexpected cloudiness, sediment, odor or other changes.
• pH and inhibitors: where required, test using the fluid supplier's methods and limits.

Follow the replacement intervals and test limits specified for your equipment and fluid. An incorrect concentration may be adjusted after testing. Contamination or fluid deterioration may require draining, cleaning and refilling the circuit.

What Should You Avoid Putting in a Glycol Chiller?

Do not substitute automotive antifreeze or RV winterizing fluid unless the equipment manufacturer explicitly approves the exact product. A label mentioning glycol does not establish compatibility with a continuously circulating beverage cooling system. Plain water is unsuitable where the equipment requires freeze protection.

Coolflow DTX is a different fluid altogether. Its maker describes it as a fully inhibited, low-toxicity coolant based on detoxified ethylene glycol. It isn't propylene glycol, so use it only if your chiller maker approves it.

Do not mix DTX with PG, and do not use the DTX concentration chart for a PG mixture. If you switch fluids, get the flushing and refilling procedure first.

Where Can You Buy Food-Grade Propylene Glycol?

We sell USP grade, food-grade propylene glycol for brewery and draft systems. Work out your full loop volume, then pick a size: 1 gallon, ships from the USA, 1 gallon, ships from Canada or a bulk drum.

Browse brewery chillers for fermentation and cold crash, or draft glycol chillers for long-draw dispensing. When a pump wears out, match the replacement pump or motor to the original model and voltage.

Frequently Asked Questions

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• How to Size a Glycol Chiller for Your Draft Beer System
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• Glycol Draft Beer System Components and Cost