Pre-filter

The micron ratings of a cartridge are intended to indicate the smallest particle that will be retained by the pores of the filter element. Often a rough-cut pre-filter is installed ahead of a final or polishing filter in order to increase the life of the final unit. Unfortunately, the method for determining the micron rating is not a universal standard between manufacturers. Thus, one manufacturer s 50 micron filter may not perform the same as another manufacturer s with the same rating number. The only reliable approach is to send the manufacturer an actual sample of the fluid and let him test it to select the filter to do your job, or actually test the unit in your plant s field application [37]. 

In-line high-pressure pre-filter assemblies with ESA carbon filter element Model 5100A Coulochem Detector with Model 5010 analytical cell and Model 5020guard cell ESA, Inc. 

Figure 1. An example of CW-type system 1. probe 2. data processing unit for pre-filtering and managing control signals 3. power supply 4. laptop computer for recording data and sending control signals to the probe 5. computer for hosting the task.

Airborne particles, bacteria, fungi spores and allergens will be removed by air filtration, which is often cheaper and more effective than electrostatic precipitators and ionizers. A disposable, high-efficiency filter capable of removing at least 95 percent of particles with size down to 0.3 micron will be installed. A washable coarse filter that removes fifty percent of particles larger than 10 microns will be used as a pre-filter to extend the life of the high efficiency filter by at least a third. An inexpensive sensor will be included to indicate when filter replacement is necessary. 

Specifications included two 56-gallon FIDPE tanks, a 120 V pump, on/off float switch, rotameter with flow-rate adjustment, two pre-filters, and four filters with refillable Octolig cartridges. Size is 52"x52" with a 68 gallon spill containment. From [28] and reproduced with permission. 

Figure 16.10—Quadrupole filler. Ions, depending on their mass, will react differently to the AC voltage. A model of a quadrupole filter with a pre-filter is shown (Fisons).

Scheme 2. Affinity chromatography bioreactor (ACBR) for the semi-continuous recovery of plant-produced proteins. Media is drawn up through the intake nozzle (D) during culture, through a pre-filter (B) that removes particulates, and then to a protein-collection column (C) using a peristaltic pump. After protein binding, the media is returned to the growth chamber. Humidified air is supplied to the culture through a sterile pre-filter (A) [62]...

High-turbidity samples can clog filters reducing the effective pore size. To avoid this, glass fibre pre-filters should be used and clogged filters changed regularly. 

Excessive pressure drop through the pretreatment system, including the pre-filter installed on the RO. 

TABLE 6.4. Product quality and yield of esters from pre-filtered and unfiltered acid oil. 

A dynamic flow method was used to determine the rate of pheromone release from the various matrices. A vacuum manifold was constructed for multi-sample analysis. The sample chambers were modeled after the design of CrossQ) and consisted of a glass chamber fitted with a charcoal pre-filter and absorbent column. 

When the three-dimensional structure of the target is unknown, pharmacophore approaches play a predominant role among the compound selection filters that have been designed for retrieving bio-active molecules. Additional pre-filtering based upon favorable physicochemical properties necessary for, e.g., oral bioavailability, aqueous solubility, metabolic clearance, and chemical reactivity or the presence of toxic chemical groups,clearly will enhance the success rate of finding possible candidates for further optimization. 

For the virtual screening, the Asinex, IBScreen and Maybridge vendor subsets were obtained from the ZINC site. In total, these databases contain 876 930 structures. After the normalization and structural pre-filtering steps, a focused screening subset of only 58 structures was obtained. We used somewhat relaxed structural filtering criteria in the hope of identifying possible distantly... 

Plugged frit, pre-filter, guard column plugged inlet frit Backflush column/cartridge. Replace frit, pre-filter, guard column replace endfitting or frit assembly. 

Reverse osmosis This hyper-filtration method uses both pre-filters (such as activated carbon) and membranes with unbelievably small pores to trap contaminants. As such, it is effective for bacteria and viruses, arsenic, fluoride, nitrates, and most of the substances identified above. It is moderately effective on VOCs and hydrogen sulfide and ineffective on radon. 

Figure 19.6 Decrease of percentage of positive results in the Ames test by applying an in silico pre-filter in Hoffmann-La Roche Ltd.

If in-vitro assays are to be used for total estrogenic load (as effects have been shown to be additive) and as such as a pre-filter for LC-MS analyses, a better traceability in the results is needed. This can be obtained by the use of certified reference materials and participation in inter-laboratory exercises. Unfortunately, there are no commercially available reference materials (which should be natural samples) to date, nor is there any organization of open regular inter-laboratory exercises, which should be given priority in the future. Thus, there are issues which remain to be solved, but initiatives to solve these problems are on the way, so this is hopefully only a question of time. 

We used a simple on-demand 60 psi Flojet pump with pre-filter to screen particulates. Pump system activation can proceed from level indicator and or manual feed and cutoff. 

Wherever the outlet is, a strainer/filter of at least 40 mesh screen should be placed over the outlet on the inside of the reservoir and epoxied in place. If a pre-pump filter is placed just before the pump in the system, this is not necessary. However, the screen is less expensive than buying a pre-filter, and it is easy to make. 

---