Selecting the Right Vacuum Pump for Filtration of Various Types of Vapours
Vacuum and pressure filtration is used for sample preparation in chemistry, life sciences, environmental analysis, and pharmaceutical quality control. The goal is to separate a solid product from a liquid mixture or solvent. Filtration rates are accelerated by creating a differential pressure across the filter unit by applying either vacuum or pressure.
The WOB-L® oil-free vacuum pumps employ an aluminum piston with PTFE seal and are loaded with powerful features for vacuum or pressure filtration. The diaphragm pumps are available in different head/diaphragm materials to handle a range of chemical vapors evolved during filtrations.
With these two pump mechanisms and range of materials available, Welch can offer a pump to fit your specific application and budget needs. A modest vacuum of 40 torr (53 mbar) to 200 torr (266 mbar) is normally sufficient (26 in. Hg to 29.6 in. Hg) for most vacuum filtration applications.
Free air displacement requirement for vacuum filtration is dependent on the filter size, leak rate, condition of the filter cake, and number of filter holders. Pressure filtration normally requires from 2 to 6 bar (30 PSIG to 88 PSIG).
Models 2522, 2534, 2546 These single headed, WOB-L® vacuum pumps are standard duty dry pumps and are effective for filtering aqueous or buffer solutions that are not strongly acidic or basic. Flow ranges from 16 lpm to 45 lpm@60Hz and vacuum from 26 in. Hg (133 mbar) to 27.6 in. Hg (80 mbar). Features on these models include vacuum and pressure regulators with
gauges, liquid trap at inlet with ball valve to prevent accidental ingestion of solution into pump, and a silencer on outlet for noise reduction.
Model 2567 A twin head WOB-L® vacuum is a standard duty pump with a flow of 100 lpm@60Hz and vacuum to 27.6 in. Hg (80mbar). Configured with an inlet catch-pot, vacuum regulator/gauge and exhaust silencer, this pump can handle up to a 6 filter holder manifold.
Model MPC 090 E Diaphragm pump configured for filtering weak acid/base solutions. Pump comes with an inlet regulator and a catchpot. Flow of 16.7 lpm and ultimate vacuum of 27 in. Hg(100 mbar). Option available with power adapter to connect with a vehicle to permit use in the field.
Models 2050, 2060 These Gemini diaphragm pumps are configured for lab or field usage to do sampling or filtration. Gemini pumps have polyacrylamide heads and viton diaphragms, tubing and valves making them ideal with water, light organic solvents and weak acids/bases. Flow of 13 lpm and vacuum to 22 in. Hg (266 mbar). Model 2050 is pump only. Model 2060 comes with vacuum gauge/regulator assembly. Includes automobile power adapter for field use (12V DC to AC).
Diaphragm vacuum pumps with chemical resistant construction are suitable for filtering organic solvents, acids and bases. For this reason, diaphragm pumps are com-monly used in applications like filtering precipitate in syn-thesis reactions and solid phase extraction (SPE).
Vacuum level for these models achieve a deep enough vacuum to create a pressure differential in filtering flask with atmospheric pressure to speed filtration. At the same time, the pumps are selected so as not to generate too deep a vacuum to lead to “boiling” of most filtrates collected in the filtering flask.
Model 2019 Economical, light weight, durable diaphragm vacuum pump with PTFE contact surfaces for filtering light organic solvents, weak bases and acid solutions. Material of construction is PTFE coated aluminum, PTFE liner for the diaphragm and fluorinated plastic inlet fitting. Maximum vacuum of 24 in. Hg (200 mbar). Flow of 37 lpm@60Hz. Pump can be used to pressurize up to 18 PSIG. Includes exhaust muffler and also hose fitting to channel exhaust fumes to a fume hood.
Models 2014, 2037 and 2047 DryFast® Chemical duty PTFE diaphragm pumps are effective for filtering organic solvents, acidic and basic solutions. These rugged oil-free pumps handle aggressive vapors since they are corrosion resistant with all PTFE head construction, PTFE diaphragm, fluoroplastic valves and fittings. Built-in vacuum regulation using a bleed valve mounted on the front panel. Flow ranges from 35 lpm to 70 lpm@60Hz. Ultimate vacuum to 28.3 in. Hg (53 mbar).
Models MPC 301 E, 601 E and 602 E These one stage models of MPC chemical duty PTFE diaphragm pumps are effective for filtering organic solvents, acidic and basic solutions. The MPC models use PTFE and other fluorinated plastics for the wet-ted parts to allow aggressive solvent and acid vapors to be pumped. Flow ranges from 38 lpm to 70 lpm@50hz and ultimate vacuum pressure from 75 mbar (27.7 in. Hg) to 30 mbar (29 in. Hg). Optional vacuum regulators with gauges can be mounted on the inlet of the pump to regulate the vacuum level by way of a bleed valve.
