Control foot-operated

Foot-operated bellows fitted with a rubber disc enclosed in a string net, to provide an air reservoir, give a steady pressure of about 20 oz/in. They are suitable for air-gas flames of moderate size. Bellows with a spring-controlled reservoir can also be used, but they do not give such a steady pressure. 

Microinjector. The purpose of a microinjector is to deliver a reproducible injection volume into oocytes, usually in the range of 2-50 nl. We use an automatic microinjector that uses compressed nitrogen to force liquid from the injection needles (model PLl-100 picoinjector microinjector from Medical Systems Corporation). The system delivers constant volumes and has a number of useful functions (e.g., fill, hold, balance, and clear functions) controlled by foot-operated switches. Simpler and less expensive automated injection devices are also available (e.g., Nanoject, variable from Drummond Scientific Company) and will suffice for nuclear and cytoplasmic injections. 

Equipment is considered the primary barrier for protection of the employees. Items such as biosafety cabinets, safety centrifuges, enclosed containers, impervious work surfaces, autoclaves, foot-operated sinks, and other equipment specifically designed to prevent direct contact with infectious organisms or with aerosols must be available. Personal protective equipment can also be considered as an effective secondary barrier if engineering controls are not sufficient. These latter items can include, at minimum, a lab coat or wrap-around gown, possibly gloves, masks, or respirators, goggles, and head and foot covers. 

Historically, press controls have lagged behind other machine tool controls due to the simplicity of requirements needed to operate a press. Originally, all that was needed was a motor start-stop button. In the old line-shaft machines where one motor ran one shaft with multiple machines connected to the shaft, an actual electrical control was not required. Actuation took place with a mechanical, usually foot-operated lever that engaged the clutch, which then operated the slide. 

Another type of control guard is a cover over a switch, knob, or button. Covers may be full or partial. A full cover totally encloses the control. An operator must move the cover or a portion of it to access the control. Full or partial covers are common for foot controls when there is a danger of some object falhng on the control and activating it. For frequently used controls, covers may introduce inconvenience and cause someone to remove them. Designs other than covers may be better. 

Where the foot is used to control a machine, the heel should rest on a support and in operating the control the foot should only need to be raised (extended) a minimum amount and the control actuated by flexing the foot to give a fine degree of control. Foot controls that require the whole foot to be raised allow only very coarse control and are best restricted to operations that require only a simple either/or position of the control. 

Condenser tail pipes, used tvith any condenser, are sealed with a 34-foot leg into a sump, or with a condensate pump operating under vacuum on suction. With surface-type condensers, the level may be sealed in a receiver with a float or other type of level control. 

Working areas within certain industrial buildings may have restricted access (i.e. sterile laboratories, radioactive areas). Separate toilet accommodation may be required in these areas, an assessment of which may be obtained from the operator and reference to such publications as Atomic Energy Code of Practice, Laboratory Practice. It may also be necessary to operate such appliances remotely by photoelectric cell, sonic control or foot control. 

Performance. So far, the deep-basin still has been operated only under batch-type control—that is, without continuous blowdown or heat exchange to the incoming sea water. In determining the performance of the still, incident solar radiation and distillate production are measured daily. From this information, the specific production in gallons per square foot per day and the thermal efficiency can be determined. In addition to the daily collection of performance data, hourly collections are made during periodic energy- and mass-balance runs. 

FIG. 14-127 Prediction of venturi-scrubber cut diameter for hydrophobic particles as functions of operating parameters as measured by Calvert [Calvert, Goldshmid, Leith, and Mehta, NTIS Puhl PB-213016, 213017, 1972 and Calvert, J. Air Pollut. Control Assoc., 24, 929 (1974).] uG is the superficial throat velocity, and AP is the pressure drop from converging to diverging section. To convert meters per second to feet per second, multiply by 3.281 to convert liters per cubic meter to cubic feet per cubic foot, multiply by 10-3 and to convert centimeters to inches, multiply by 0.394. 

Electrically controlled connections to the inert gas supply and the vacuum pump line which are capable of maintaining any desirable pressure inside the box. This control system should include pedal switches to allow operation by foot while the hands are engaged inside the glove box. 

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