By-pass valve

In general, the downhole turbine motor is composed of two sections (1) the turbine motor section and (2) the thrust-bearing and radial support bearing. These sections are shown in Figure 4-191. Sometimes a special section is used at the top of the motor to provide a filter to clean up the drilling mud flow before it enters the motor, or to provide a by-pass valve. 

Valve 29 in line 14 is a quick opening bypass valve which is normally closed. However, in case of an emergency shutdown, this valve can be instantly opened to shut off the supply of alcohol to the reaction zone and return the alcohol stream via line 31 to alcohol supply tank 11. Such a quick opening by-pass valve normally is not employed in the nitrating acid line, since in case of an emergency shutdown, nitrating acid is employed to sweep out the tubular reactor... 

By-pass lines for pumps and compressors, with a connecting line from the pressure-side to the vessel on the suction-side. This safety risk is eliminated in most cases by using a check-valve in the discharge line after the branch to the by-pass valve. 

Relatively high compression ratios can be achieved with Roots pumps at high vacuum pressures but there is a maximum pressure difference (Apmax) at which they can be satisfactorily operated. This is determined predominantly by the temperature rise of the gas at the exhaust of the pump. Pump manufacturers specify Apmax in their data for Roots pumps and it refers to continuous operation of a pump with no additional control features such as by-pass valves and similar devices. 

Fig. 7. Diagram of a fluidized bed crystalliser. A, Calming section to reduce large eddies B, reaction zone C, by-pass valve D, flow meter E, cooling coil F, solution reservoir.

During normal operation the flare valve is closed and the pressure in the gasifier is controlled through a by-pass valve at the booster compressor. Quite naturally is the gasifier a slow system concerning both pressure and temperature control. The output control of the gas turbine is completely different and it responds more or less instantaneously. Operation in the fully integrated mode made the pressure, temperature and gas quality in the system vary a bit when the gas turbine suddenly compensated for a small change in either parameter. 

Nitration starts in 6 and continues in the tubular nitrator before entering the cooler and finally the separator. Valve 5 is a quick opening by-pass valve. In the case of an emergency valve 5 is turned to stop the flow of glycerine to the nitrator 6 switching through 7 to the glycerine container. 

To circulate coolant through the apparatus, open both shut-off valves and slowly open the flow control valve, adjusting it to the proper flow. If completely opening the control valve gives insufficient circulation, slowly closing the by-pass valve will further increase the flow. It is important to remember that the flow rate will vary according to the temperature of the coolant. 

To deactivate the cooling system, fully open the by-pass valve and turn off the pump. With the flow control valve completely opened, residual coolant in the apparatus will be siphoned back through the inlet port down into the reservoir. Both shut-off valves are then closed. After the apparatus is disconnected from the tygon tubing, the two ends of the tubing can be mated and left in place. 

Fig. 1. General diagram (1) gas ballast (2) compressors (3) liquefier (4) liquid-hydrogen transfer line (5) automatic by pass valves (6) pipeline joint (7) pipeline joint (8) liquid-nitrogen storage tank (9) corn-pressed hydrogen reserve (10) immersed part of the loop (11) condensing area (12) liquid-neon-bath.

Process"vater System. In the water system the annular type ionization chamber is used By pass valves and conduits allow the radioactive water or gas to pass through the chamber. Activities are measured by this method at the seal tank liquid vent seal, and in the demineralized-water system. 

In an attempt to bring steam pressure up, steam by-pass valve shut... 

Figure 18.1.9. Principle of an olfactometer. 1 diluent air a) outer air, b) synthetic air (bottle) 2 acitvated charcoal filter air from 2d to rinse by-pass, 3 glass bulb pump with electronically controlled drive (a,b) 4 mix chamber (with installation a) 5 evaluator s mask 6 sample air (if necessary pre-mixed) 7 glass bulb pump with electronically controlled drive (a,b) 8 by-pass valve 9 mix chamber valve 10 crmtrol terminal, a) display (programme step), b) display, c) terminal keyboard 11 printer 1 - IV control line 12 additional pump (24 1 x min-1).

Fio. 7.1. Steam trap with strainer and by-pass valve. 

Steam traps, or the strainers that protect them, are often blocked by the accumulation of rust and dirt and it is a good practice to install a by-pass valve which enables the condensate to be removed while the strainer is being cleaned see Fig. 7.1. It is most important to ensure that the by-pass valve is closed except while the strainer or trap is being overhauled. 

The closed loop and open loop reactor dynamics are compared in Figs. 9 and 10, for a step decrease in the reactor pressure. A SISO controller was tuned to control the inlet temperature of the first bed, Toi, tl ugh the by-pass valve (see Fig. 1). When the reactor is operated without feedback control, the sudden reduction in the pressure leads to a decrease in Ae heat generation rate, the temperature Touti (and consequently Toi) decreases and the reactor moves to a lower (extinguished) steady state. This effect can be serai in Fig. 9, where the overall temperature rise drops from 230 C to 12 °C. Conversely, when the feedback control loop is included, the overall temperature rise shows a significantly lower decrease (from 230 to 199°C) as a consequence of the gradual reduction of the cold by-pass (Fig. 10). 

The tests have been performed maintaining constant the generator setpoint temperature at the value of 967°C this value of temperature is automatically maintained from the system acting on the air flow. A current variation causes a variation of the inlet air temperature this is controlled by a by-pass valve of the low temperature heat recuperator. Besides, a current variation causes a variation in the thermodynamics condition of the stack to maintain constant Tqen, the control system operates on the mass flow of the inlet air flow. 

Re-starting of the pumps or closing of the by-pass valve by reversing the pilot control takes place, when the last but one contact pin is cleared, i. e. after a cycling stroke has been performed as already explained in the operation of the shutoff valve. 

Faults in the cycle of control operations due to current failure are eliminated by the so-called closed circuit current principle , i. e. when the solenoids are deenergized, the automatic shutoff valve closes and the pump by-pass valve opens. 

Remove or spade off any control valve or instrument liable to damage under test 1 pres.sure, replace with. spool or make good joint and open any by-pass valves ... 

If no leakage is observed, bleed off the pressure using the by-pass valve. 

Remove the threaded heavy duty cover and clean the threads. Check the integrity of the plug fitting by cracking open the by-pass valve. 

Crack open the by-pass valve to allow line pressure into the retrieval tool. Allow pressure to stabilize and check for leaks. 

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