The API filter press is used to analyze filtration behavior and wall cake building characteristics of drilling fluids and cement slurries. Their stability is based on fluid loss and may be determined by measuring and describing the filter cake.
The components of the filter press are: A cell body to hold the mud sample, a base cap c/w drain tube to discharge filtrate into a graduated cylinder, a stand, a cell support including a pressure regulator with gauge, a CO2 cartridge holder or an air hose. The base cap holds an exchangeable mesh on which a 3½” (90 mm) sheet of filter paper can be placed. This corresponds with a filtration area of 7.1 ± 0.1 in2 (4,580 ± 60 mm2) recommended by the American Petroleum Institute (API).
Before the test a sheet of filter paper is placed on the mesh in the base cap. The cell body of the filter press is filled with mud or cement and the cell is closed with the base cap. A pressure of 100 psi is applied to the cell by piercing the CO2 cartridge or by compressed air from a bottle or compressor. Filtrate is driven through filter paper and the outlet in the base cap and collected by means of a graduated measuring cylinder. After a time period of 30 minutes the amount of discharged fluid may be recorded and the filter cake that has formed on the filter paper is measured and described.
As an alternative to CO2 cartridges or compressed air, the filtration pressure may be generated in a U-shape hydraulic assembly. On one side of the U there is a vertically aligned cylinder with a piston acting on a water column. A dead weight is resting on the piston, pushing the water into the other side of the U and compressing the air above the water column, thus creating the filtration pressure in the filter press cell. This filter press model does not need a pressure regulator nor an external pressure source.
The MUDTEST filter press complies with the requirements of API RP 13B-1 or the corresponding international standard ISO 10414 for field testing of drilling fluids. The requirements of the German standard DIN 4127 for the test procedure for supporting fluids in diaphragm wall construction are also met. The filter press falls within the scope of the European Pressure Equipment Directive 2014/68 / EU. Therefore, the corresponding conformity assessment procedure was carried out and the CE marking was attached.