1. A pressure filter is operating under the following conditions: Filter area: 250 sq ft Slurry concentration: constant but not precisely known Pressure drop constant at 60 psi The operating log shows that the filtrate rate was 30 gal per hr when the total volume filtered was 100 gal. Consider all resistances to be constant and r m = 0. What should the filtrate rate be when the filtrate volume is 300 gal? A. 0.10 cu ft per sec B. 30.0 cu ft per sec C. 0.0003 cu ft per sec D. 0.0001 cu ft per sec 2. A type of filtration in which colloidal particles in suspension are filtered to form a concentrated slurry and clean filtrate is A. pressure filtration. B. gravity filtration. C. ultrafiltration. D. hyperfiltration. 3. A filter is being operated under constant-rate conditions. The operating data are as follows: Filter area: 50 sq ft Slurry concentration: 1.2 lb dry solids per cubic foot of filtrate Constant filtrate flow rate: 150 gal per hr Pressure after 1.0 hr of filtration: 20 psi Pressure after 1.5 hr of filtration: 23 psi Compressibility factor: 0 What will be the pressure on this filter at the end of 4 hr? A. 49.0 psi B. 61.3 psi C. 21.3 psi D. 37.5 psi 4. You are choosing a weave of cotton filter cloth for a filtration operation in which you are using a filter press. You want to recover the filter cake, which is relatively coarse and filters easily, with little tendency to bleed or plug the cloth. The operation of your filter press requires a tough and durable weave. What weave of cloth would you use? A. Twill B. Duck C. Diagonal D. Chain 5. A continuous precoat ftlter is used for an operation in which A. the filter cloth reacts chemically with the slurry. B. the filtrate is, the desired product. C. the filter cake must be recovered. D. a large amount of compressible, slow-filtering solids are to be removed from the liquid. 6. The following data apply to a filtration problem: 1. The rate of cake formation is very fast. 2. The filtering characteristics are constant. 3. The filter cake is to be washed. 4. Repeated changes of filter cloth are necessary. 5. The liquid in the slurry is a volatile solvent at a temperature close to its boiling point (at atmospheric pressure). 6. It is desired to keep the initial cost of the filter equipment as low as possible. The type of filter needed is A. batch, based upon data I, 2, and 3. B. batch, based upon data 4, 5, and 6. C. continuous, based upon data 4, 5, and 6. D. continuous, based upon data 1, 2, and 3. 7. You are employed by a company that produces relatively small commercial batches of pure chemicals and drugs. Several of the products have one or more stages in their process of manufacture which involve filtration. You want to install a filter that is readily adaptable to filtering different types of materials and is relatively low in cost. Also, you desire a filter in which the filter area can readily be increased or reduced and the filter cloths quickly and easily changed. The space available for the filter is small, so that you need equipment providing a large amount of filter area per square foot of floor space. The profit realized on your products is high, so that the labor cost of operating the filter is not an important factor. Several of the materials have a high filter resistance, so that filtering pressures of 25 to 60 psi will be necessary. With the above requirements in mind, which one of the following filters would you recommend be purchased? A. Filter press B. Vacuum Nutsche C. Rotary-drum filter D. Pressure leaf filter 8. A pressure filter is operating under the following conditions: Filter area: 250 sq ft Slurry concentration: constant but not precisely known Pressure drop constant at 60 psi The operating log shows that the filtrate rate was 30 gal per hr when the total volume filtered was 100 gal. Consider all resistances to be constant and r m = 0. The filter will hold cake up to 1 in. thick. Cakes in the past have had a density of 20 lb dry solids per cu ft. What is the maximum amount of solids which the filter will hold? A. 450.0 lb B. 309 lb C. 416.6 lb D. 133 lb 9. ______ is a form of filtration which uses a force other than gravity, with this force acting in front of the filter medium. A. Vacuum filtration B. Pressure filtration C. Membrane filtration D. Cake filtration 10. You are requested to produce several batches of a chemical compound. The process includes a filtration step in which you want to recover the filter cake. There are no commercial filters installed in your plant, and because of the limited number of batches required, you will use the filter for only a short period. You find that the material filters rapidly and that 80 sq ft of filter area is ample to keep up with your production schedule. Because of the temporary nature of the filtration operation, it is to your advantage to keep the initial cost of the filter and the labor cost at a minimum. There is considerable floor space available to install the filter. Which one of the following types of filters would you choose? A. Filter press B. Pressure leaf filter C. Nutsche filter D. Rotary-drum filter 11. In filtering a new material you find that the filter cloth you normally use tends to decompose and fall apart. You want to select a more suitable cloth. The material being filtered is strongly alkaline, and the filtration temperature is 215 F. Which of the following filter cloths would you select as most satisfactory for the conditions? A. Glass fiber B. Cotton C. Rayon D. Dynel 12. A 60-in.-diameter centrifugal filter, operating at 296 rpm, is being loaded with a slurry consisting of a liquid with a density of 60 lb per cu ft. Assume the liquid fills the cylinder to the inside surf ace of the cake and that the dry cake has an in-place bulk density of 90 lb per cu ft. When the cake is 4-in. thick, what is the pressure on the filter medium? A. 15 psi B. 71 psi End of exam C. 22 psi D. 4 psi 13. A form of filtration in whicll the liquid is drawn through a filter medium by the existence of a pressure below atmospheric pressure behind the medium is A. vacuum filtration. B. cake filtration. C. pressure filtration. D. ultrafiltration. 14. Which of the following values for the number of displacements would usually be considered unprofitable in the washing operation of a continuous filter? The values represent pounds of wash water per pound of water in the cake. A. 2, 10 B. 1, 25 C. 3.5, 30 D. 1.5, 15 15. For which of the following conditions should a filter aid be used in a filtering operation? A. A filtration operation in which the filtrate runs clear without filter aid. However, it has been found that if a small amount of filter aid is used per batch, 3 hr of filtering time is saved. B. A coarse, free-filtering slurry C. A slurry that contains acids or alkalis D. A slurry that filters rapidly but contains fine solids that pass through the filter medium and cause undesirable cloudiness in the filtrate