When filling tankers with toxic chemicals, what precaution should be taken regarding backflow prevention?

When filling tankers with toxic chemicals, utilizing an approved reduced pressure backflow preventer is essential for preventing contamination of the water supply. This type of backflow preventer is specifically designed for situations where the potential for high-hazard backflow exists, such as when dealing with toxic substances.

The reduced pressure principle allows for a small degree of backflow under specific conditions, but it maintains a pressure lower than the supply pressure, which helps to ensure that no contaminants can siphon back into the potable water system. The device typically includes an air gap that prevents backflow from occurring if there’s a drop in pressure in the water supply line. Such a setup is crucial in protecting public health and ensuring compliance with regulatory standards.

In contrast, options such as installing a simple check valve may not provide sufficient protection for toxic substances, as they may not handle backpressure effectively. Similarly, not having an air gap is not protective and can actually facilitate contamination, which is why ensuring an appropriate backflow prevention method is vital in these scenarios. Closing the valve tightly after filling does not inherently address the risk of cross-contamination or backflow, making it an inadequate measure alone without the necessary backflow prevention device.