Filters are an essential component of irrigation systems. The main function of filters is to separate suspended or dissolved particles from the water. In irrigation, we aim to remove particles that affect plant health or the efficiency and uniformity of water distribution. Growers should select filters based on the target problem, compatibility with irrigation, and cost.
by Rosa E. Raudales - rosa@uconn.edu
In this e-Gro Alert, I will discuss some water contaminants and the filters that are commonly used to remove the target problem.
Understanding the units
The pore size of filters are rated by the mesh number or pore diameter. Micrometers (µm) —also known as microns— are the units used to measure pore diameter. Micrometer is a length unit from the International System of Units (SI) equivalent to one-millionth of a meter or one twenty-five thousandth of an inch (Figure 1). Mesh number or mesh size refers to the number of openings in one
linear inch (e.g. 100 mesh means there are 100 openings in one inch).
The numerical relationship between mesh size and pore diameter is inverse. As the pore size in microns increases, the mesh size decreases and vice versa.
Microns are the international standard unit to communicate about filter pore size and it is useful because we can compare the diameter of the pore size of a filter with the diameter of target particles. In contrast, mesh number— the American standard — is not easily relatable to the target issue.