Issue link: http://psai.uberflip.com/i/1433567
5 I PSAI Association Insight, December 1, 2021 (continued on page 6) Methanol is classed as a poison by the US Centers for Disease Control and Prevention (CDC ) 2 and symptoms of methanol exposure include nausea, vomiting, and blurred vision. Poisoning can occur by inhalation, ingestion, or absorption through the skin. In addition to the CDC advice, the US National Institute for Occupational Safety and Health (NIOSH) publishes clear guidelines for the handling and use of methanol 3 . Operators should avoid breathing in vapours or swallowing methanol solution and always wear personal protective equipment (PPE). This includes waterproof gauntlets or gloves, jacket, trousers, boots, and protective goggles/face shield. Methanol is also highly flammable if mixed in concentrations above 33 percent, which must be avoided at all times. In extremely cold weather, methanol can also be mixed with salt brine to lower the freezing point even further. With careful mixing, it is possible to prevent freezing down to -40° (which, incidentally, is the same temperature in both Fahrenheit and Celsius). However — and this is very important — liquid at these very low temperatures can cause serious injury and harm if splashed on bare skin. The freezing point of different concentrations of salt brine and methanol solution are shown in Table 3. In some jurisdictions, methanol is also subject to special conditions when transported by road — so operators must check local road transport regulations for the carriage of Dangerous Goods if they plan to transport methanol by road for use in their restrooms. Environmental Impact In researching this article, I also spoke to environmental engineer Darryl Veale about the effects of methanol on the environment. Listeners of the Get Flushed podcast may remember Darryl from Season 1. He's the engineer in charge of the wastewater treatment team at Christchurch City Council in New Zealand. When I asked Darryl about methanol, he said that while he'd prefer it not to enter the wastewater system, any methanol used in portable restrooms will be so diluted by the time it reaches the sewer that it is unlikely to present any problems. Because it is classified as a poison, (continued on page 6) Winterization: How to Prepare Restrooms and Equipment for Extremely Cold Weather (Part 2) (continued from page 4) CONCENTRATION OF SOLUTION METHANOL DOSE (FL OZ PER GAL) METHANOL DOSE (ML PER LITRE) FREEZING POINT OF SOLUTION 5% 6.4fl oz 50ml -6°F (-2°C) 10% 12.8fl oz 100ml -11°F (-°5C) 15% 19.2fl oz 150ml -17°F (-27°C) 20% 25.6fl oz 200ml -21°F (-29°C) 25% 32.0fl oz 250ml -30°F (-34°C) 30% 38.4fl oz 300ml -40°F (-40°C) Table 3. Mixing Guide: 20% Salt Brine with Methanol Solution NOTE 1: Contact with bare skin at very cold temperatures can lead to serious injury and harm. Correct PPE must be worn when handling these solutions. NOTE 2: Methanol can be flammable when mixed with water. Do NOT exceed a methanol:water concentration greater than 33 percent.