Pneumatic and Hydraulic Equipment

IMPORTANT Before you start please read the following instructions carefully. 1. This assignment forms part of the formal assessment for this module. If you fail to reach the required standard for the assignment then you will be allowed to resubmit but a resubmission will only be eligible for a Pass grade, not a Merit or Distinction. You should therefore not submit the assignment until you are reasonably sure that you have completed it successfully. Seek your tutor's advice if unsure. 2. Ensure that you indicate the number of the question you are answering. 3. Make a copy of your answers before submitting the assignment. 4. Complete all details on the front page of this TMA and return it with the completed assignment including supporting calculations where appropriate. The preferred submission is via your TUOL(E) Blackboard account: https://eat.tees.ac.uk 5. Your tutor’s comments on the assignment will be posted on Blackboard. 1 Teesside University Open Learning (Engineering) © Teesside University 2011 1. (a) Draw a pV diagram to illustrate the operation of a two-stage compressor with intercooling. (b) List the advantages to be gained by the use of a multi-stage design compressor. 2. (a) With the aid of a sketch, describe briefly the operating principle of a rotary vane compressor. (b) State the reasons why oil must be injected into this machine for its efficient operation. 3. (a) A mass of 400 kg is to be raised by the actuation of two identical hydraulic cylinders with a piston diameter of 120 mm. Calculate the required system pressure to just raise the load. (b) If the load is to be raised 600 mm in 10 seconds, what will be the required flowrate (Q) in min–1? 4. Describe the operation of a variable displacement axial piston (swash plate) pump, indicating the means by which its output is varied. 5. With reference to basic constructional features, contrast the methods of compression employed by positive displacement and dynamic air compressors. 6. An item of plant requires 2 m3 min–1 of pulsation-free and oil-free compressed air supplied at a pressure of 7 bar. Select and size a suitable type of machine with regard to output FAD (free air delivered) and quality of air supply. 2 Teesside University Open Learning (Engineering) © Teesside University 2011 7. Air is drawn into a compressor at normal temperature and pressure (N.T.P.) and compressed to a pressure of 6 bar gauge. After compression the air is delivered at 1.2 m3 min–1 and cooled to a temperature of 30°C, at which point condensate is collected at the rate of 2 litres per hour. Estimate the FAD (N.T.P.) of the compressor, and the relative humidity of the air entering the compressor. 8. Describe the difference between regenerative absorption and chemical absorption air drying. 3