Filter bag or cartridge?
Start with the solids load, required retention and maintenance method. Compare usable filtration area, pressure loss, change-out access and consumable cost at your actual flow. Neither format is a universal replacement for the other.
Nominal or absolute micron rating?
A micron number alone does not define removal efficiency. Ask for the retention efficiency, particle size, test method and conditions associated with that rating, especially when matching an existing element or protecting downstream equipment.
Which media and seal material?
Review the fluid composition, concentration, temperature and cleaning process against every wetted component. Ask for a compatibility review of the complete configuration, including media, support, end caps, seals and housing.
How do I measure a replacement?
Record the full reference, overall length, outside and inside diameters, openings, end-cap style, seal dimensions and flow direction. For pool filters, also record threads and handles. Include photographs and a dimensioned drawing where possible.
What does a flow figure mean?
Compare flow data only with the fluid, temperature, viscosity, filtration rating and clean differential pressure stated. Confirm whether a published limit refers to the element or the housing. Housing design pressure, working pressure and element differential pressure are separate values.