Recently, an employee at a chemical plant was accidentally exposed to a caustic solution that the plant was processing. He ran to the nearest safety shower in order to rinse the caustic off. Unfortunately, the safety shower was malfunctioning.

Instead of tepid water in the 85°F (29° C) range, he was doused in water under 60° F (15.5° C). His initial reaction was to jump out, but his fellow employees held him under the cold water to rinse off the chemical. As a result, he ended up with hypothermia from the cold water.

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Avoid permanent injury, freeze damage and corrosion.

In brief:

• Federal regulations require you to flush supply lines to emergency showers and eyewash stations weekly.
• The water passing through these devices must be at a temperature between 60°F and 100°F.
• The showers/eyewashes must be placed strategically, depending on the plant’s physical layout.

Regulations and standards are intended to help keep employees and processes safe. Water temperature can mean the difference between whether an employee incurs permanent injury in an accident, whether outdoor processing facilities avoid expensive freeze damage, and whether a plant can keep operating without extensive maintenance. These matters are critical to operating a safe, compliant, and efficient plant. Continue reading →

Freeze protection valves are effective in preventing freeze damage in process lines. Unlike steam or electric tracing, which require power and can cause water to overheat, freeze protection valves operate by simply draining or bleeding water as the temperature approaches freezing.

This prevents the formation of ice that can clog lines, shut off the flow, and cause pressure within the line to build, cracking pipes, valves, and fittings and damaging equipment. Damage due to ice formation can incur costs for replacement parts and labor and reduce productivity due to shutdowns.

Nonetheless, freeze protection valves do not necessarily completely prevent the formation of ice. In some cases, ice may still form as a layer on the inside of a pipe. This acts as a good insulator, reducing further heat loss to the cold outside air. Also, no damage will occur if the ice does not completely block the pipe or equipment flow area.

Damage due to freezing is caused when a pipe or flow passage in equipment is completely blocked. Then, as additional ice forms, the expansion associated with the ice formation compresses the water and causes a dramatic increase in the internal pressure in the line. When the pressure exceeds the pipe’s or housing’s strength, these will break.

Valves vs. Tracing

When to Use Tracing

Tracing is required when the temperature to be maintained is above the resupply water temperature; that is when additional heat input is required. Use tracing if the complexity of the equipment layout makes it difficult or impossible to bleed or drain the system properly. Also, tracing should be used if the discharge from bleeder or drain valves presents a handling problem. This may be the case in plant areas where all discharges must be controlled or reported or where discharge treatment problems and expenses outweigh the benefits of bleeder/drain valves.

When to Use Valves

Valves are generally more economical to install and operate than tracing. Use valves in remote plant areas where steam or electricity are not available and the cost to provide them is high. Also, use valves when potential overheating from tracing is a problem. In critical applications, where power failures will cut off electric or steam tracing, select self-operating valves as the primary or backup freeze protection system.

Click to read more about how Freeze Protection Valves Keep Lines Flowing.

Australia has the highest average amount of solar radiation of any continent, making it the perfect place for generating power or heating water with energy from the sun. Not surprisingly, the combination of generous rebates and sunny weather has given rise to solar thermal installations across the continent. Generally these installations are quite straightforward, but in the southern part of the continent, temperatures can drop below zero (Celsius), causing freezing problems for some thermal systems.

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Facts About Water Freezing

Water, when it freezes, changes from liquid to solid. As the temperature drops, the molecules become less energetic, moving more slowly, until they reach a point at which the molecular structure changes, followed by the transformation into ice, or solid water. Unlike most substances which shrink in volume as they freeze, water expands since ice’s molecular structure takes up more space than water. Conversely, when you heat water, the molecules become more excited until they reach the point where the water vaporizes and becomes steam.

There is a misconception that if water can be kept moving, it won’t freeze. Wrong! Water freezes at 32°F (0°C). Period.

Since the expansion of water as it freezes is a fact of life, what things should we know about this process in order to create effective means of dealing with it in industry? Water that has frozen in piping systems does more than simply clog the system and shut off the flow. Because ice takes up more room than liquid, when freezing occurs in a confined space like a steel pipe, the ice will build up extreme internal pressure which is often enough to break the pipe and its associated valves and fittings.

Damage from a burst pipe or valve can escalate beyond just replacing the broken parts, into labor costs for the repair and time/money lost from “down-time” in the affected area. Before effective measures can be taken to prevent such disasters, we need to learn about and understand what is happening.

The Physical Principles of Freezing

What are the underlying principles that determine whether the water in a given device (pipe, valve, etc.) will freeze? We already know that water freezes at 32°F. To arrive at this temperature, heat must be removed (transferred) from the water (Remember – heat always travels from high temperature areas to lower temperature areas). Heat transfer, or the removal of heat from one place to another (i.e. from the 45°F water inside a pipe to the 25°F air outside a pipe) is one of the basic laws of nature. Heat is a form of energy. Others include chemical, electrical, mechanical and nuclear, and each is convertible from one form to another. In the USA, heat is usually measured in BTUs, or British Thermal Units. One BTU is the amount of energy which, when added to one pound of water, will raise the temperature of that water by one Fahrenheit degree (as from 65°F to 66°F).

Click here to read the full article “Basics Of Freezing“