WATER SAMPLERS

Understanding the application is the key to determining which type of sampler will best suit the requirements specified. There are several steps in choosing a sampler to ensure that you end up with a sampler well suited to your application.

Firstly, define what you want to accomplish in the application. Take into consideration your current needs and try to project your needs for the future. Your requirements should encompass both, if possible, but adding in requirements that aren’t necessary will make it more difficult and increase the cost of the sampler.

Secondly, talk with a manufacturer or manufacturer’s representative about whether their sampler can perform to your application requirements. Be specific about the fluid and contaminants that will be sampled, the analysis to be performed, the trigger for the sampler (external input, analog or serial etc), the sample storage, the positioning (proximity to a power source), and environmental conditions affecting the sampler as it may require the use of an optional enclosure for protection from the elements.

Thirdly, understand how to install and use the sampler correctly in your application. Asking questions about installation before the purchase can save many headaches and last-minute problems during an installation.

Both peristaltic and vacuum/compressor samplers operate on the same principle. The sampler intake hose extends into the source fluid. The air is evacuated from the intake section/hose, causing the fluid to flow in.

There are two factors that affect the fluid flowing in (transport), the strength of the vacuum and how fast air is removed. The stronger the vacuum the greater vertical lift a fluid sampler can achieve and the faster the air is removed the higher the fluid transport velocity.

Vacuum samplers have the advantages of faster transport velocity, no expense for tubing that wears out, repeatable sample volume that is not affected by changing vertical lift and less affected by particulates. Vacuum samplers can have a higher initial cost, but with not tubing to replace are often less expensive over time.

Peristaltic samplers have the advantages of easy conversion to toxic fluids, less initial cost and keypad entry of sample volume. Peristaltic samplers have a tube that wears out, but this can be remedied easily by changing the tube.