What is sample cooler ?

A sample cooler is a small shell and coil heat exchanger. The sample to be cooled (or heated) flows through the tube side of the cooler.The cooling fluid, usually water, flows through the shell side of the cooler. A sample cooler is used to cool a sample from a process stream. Because the process stream is usually hot water or steam, sample coolers are used to cool the sample. When high accuracy is desired, the sample must be cooled to exactly 77°F. The cooled sample is then taken to a laboratory for analysis or, in some cases, piped to .in-line process instrumentation

A sample cooler serves for safe sampling, cooling and if applicable condensation of hot fluids. Sample Coolers are one of the most critical elements of any sampling system. They can be used for most applications in liquid, gas or steam process. Sample Coolers are small shell and tube heat exchangers that cool the sample from a process stream to the required temperature conditions for a safe and immediate analysis to be performed.

Sample coolers are not only used to cool samples but also to temper the sample to the appropriate temperature for the analysis being performed. This is important as some analysis procedures can be affected by interference’s directly or indirectly due to the fluid temperature.

Sample Cooler Design

Sample coolers are mainly constructed from 2 parts: a one piece heat transfer tube which is twisted to form a coil, called tube, and a cylindrical housing known as shell. The sample to be cooled, usually steam from the boiler, is inserted from the top to the tube side of the cooler, and the cooling fluid which usually is water, flows through the shell side. The Sample cooler is mostly mounted in a vertical position and the process fluids ae passed through the shell and tube in an opposite direction. This is to ensure optimum efficiency. The cooling fluid absorbs the heat of process fluid, resulting in a drop in the process fluid temperature. The cooled sample then is taken to a laboratory for analysis or piped to in-line process instrumentation for continuous monitoring of properties such as conductivity, pH, TDS or other chemical constituents.

The shell is mounted through flanged connections and it can be removed without disturbing sample lines. The sample cooler should be installed as close as possible to the system take of point at a height to facilitate convenient operation.

Features of Sample Cooler

• Low pressure drop
• Corrosion resistant
• Safe and accurate sampling
• High efficiency: Outlet temperature is very close to what is desired
• Designed to handle high pressure & high temperature samples
• Easy maintenance. Coils can be cleaned or replaced, if required, easily.
• Self-draining design to eliminate sample retention. (inlet top, outlet bottom).

 Sample cooler Installation:

For Sample cooler Installation, we must ensure the safety of the operator and the optimal performance of this equipment. The sample cooler must not be installed or used in any manner other than that which is specified in this manual.

Prior to installing, removing or maintaining  sample cooler, ensure that the equipment is isolated from all connecting piping, the equipment is de-pressurized, the contents have been drained and the equipment is cool.

If cooling water valves are installed, a relief valve or 3-way valve must be provided. Damage to the equipment may occur if a relief valve or 3-way valve is omitted.

1. Support the Sample cooler by its bracket(s) (included with the cooler) using included nuts or by water lines only. Care should be taken to avoid any additional loading on either the tubes or the cooling water piping.
2. The cooling water should be softened and free of chlorides. Any hardness in the cooling water will result in scale build-up on the coil and a loss of heat transfer capacity. Chlorides can cause pitting or stress corrosion in stainless steel. If no source of acceptable cooling water is available, consult Sentry for a recommendation. Sample Cooler 750-286 3
3. Provide a globe (not gate) valve in the cooling water outlet line for throttling purposes. Valve size must be the same as the cooling water outlet connection.
4. If isolation of the cooler is desired, provide a gate or ball valve (not globe) in the cooling water inlet line. Valve size must be the same as the cooling water inlet connection.
5. Install a relief valve in the cooling water line between the cooler and the outlet or the inlet valve. This protects against excessive shell side pressure in the event of (a) a leak in the high pressure tubing, or (b) an operator turning on the hot sample flow with both cooling water isolation valves closed, thus boiling the coolant and pressurizing the shell. As an option, a 3-way valve can be used on the inlet. It should be oriented so that the shell is open to drain when the cooling water is shut off.
6. A 90° bend or expansion loop must be provided in the hot sample line to the cooler. This allows the tubing to expand and contract with temperature changes without out inducing stress at the point where the tube is welded to the cooler head.
7. Mount the cooler either vertically or horizontally (preferably vertical on high temperature lines).
8. Installation of a sample flow control valve in the sample line after the cooler is recommended. The valve should be a multi-turn type to allow for more precise flow control. The valve should be specified in accordance with the operating pressure and temperature of the sample.
9. Installation of a sample flow isolation valve in the sample line prior to the cooler is recommended. The valve should be specified in accordance with the operating pressure and temperature of the sample.