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95 2019 INDUSTRY RESOURCE DIRECTORY FREEZING: PROTECTING YOUR UNITS Most portable restroom operators will face freezing conditions from time to time. Here are several options for servicing units during periods of extreme cold. We suggest using rock salt and/or brine, methanol, or a combination of these ingredients to protect units from freezing. Other salts and antifreezes will perform well; however, because of their prohibitive costs, we have found them to be impractical for everyday use. Below are listed the amounts of salt, methanol, or salt and methanol combined that are necessary to protect water from freezing at various temperatures. Two pounds of salt is the maximum amount that can be dissolved in one gallon of water. CAUTION: Methanol becomes flammable if used in quantities exceeding 30%. Not all jurisdictions allow methanol. Brine Solution Brine is a common and reasonably effective method of preventing freezing in the tank. One of the most common methods of making a brine solution is to purchase rock salt by the bag or in bulk. Purchase a 300-gallon stock tank (cattle feeding). Take a 55-gallon drum and cut out one end. Place the 55-gallon drum in the stock tank with the open end up. Put a pipe in the 55-gallon drum. Empty salt pellets into the drum. Run water into the pipe so that the water comes up through the salt, overflowing the top of the barrel as a brine solution. Pump brine into the truck for service work. It may also be helpful to put rock salt in the urinals so that you do not dilute the mixture. CAUTION: Do not wash units with brine solution, as you will have a white salt residue, which comes off on clothing. Use a little methanol in your washing solution for scrubbing and cleaning. Some firms use a combination of methanol and brine. Never use more than 30% methanol in the mixture. Methanol can become flammable. It burns very hot and you cannot see the flame. If a heater is put in the units, do not allow any methanol to be splashed into a ribbon heater. Methanol on a ribbon heater produces a deadly gas. The only acceptable heater is a calrod heater. The element is about the thickness of a pencil. Check with local disposal site facilities when using salt or methanol. 1/2 pound per gallon of water protects to 26˚F. 1 pound per gallon of water protects to 19˚F. 1-1/2 pounds per gallon of water protects to 11˚F. 2 pounds per gallon of water protects to 0˚F. 5% or 6.4 ounces per gallon of water protects to 28˚F. 10% or 12.8 ounces per gallon of water protects to 22˚F. 15% or 19.2 ounces per gallon of water protects to 17˚F. 20% or 25.6 ounces per gallon of water protects to 11˚F. 25% or 32 ounces per gallon of water protects to 4˚F. 30% or 38.4 ounces per gallon of water protects to -4˚F. 5% or 6.4 ounces per gallon of salt water protects to -6˚F. 10% or 12.8 ounces per gallon of salt water protects to -11˚F. 15% or 19.2 ounces per gallon of salt water protects to -17˚F. 20% or 25.6 ounces per gallon of salt water protects to -21˚F. 25% or 32 ounces per gallon of salt water protects to -30˚F. 30% or 38.4 ounces per gallon of salt water protects to -40˚F. SALT METHANOL SALT AND METHANOL COMBINED The amounts of methanol listed below are added to previously mixed solution containing two pounds of salt per one gallon of water: Better worksites. Better weekends. Better world. EXCLUSIVE MEMBERS-ONLY CONTENT REDACTED Join us now at www.psai.org for access to this valuable information.