Reaction torque

Note With a Dyna-Drill downhole motor there will be a left-hand reaction torque therefore, the tool should be turned counterclockwise from the ideal position. 

One final problem encountered with stirring was related to the strength of the aluminum fan. The adapter on the aluminum fan was not sufficient to withstand the reaction torque generated by the density of the SCF and subsequently allowed the fan to spin on the adapter and deform the fan blades. The aluminum fan was removed and a three-blade polished stainless steel mixing propeller was procured. The magnetic drive assembly was removed and the shaft... 

By the third law of Newton, for every force there is a counterforce, collinear, equal and opposite in direction. As the impeller shaft rotates, the motor tries to rotate in the opposite direction, but it does not because it is bolted in place. The tensions in the stationary motor base can be measured by a reaction torque transducer. 

Reaction torque is a less expensive alternative to direct impeller torque and is recommended for mixers that have the motor and impeller shafts axially aligned (in this case, the reaction torque is equal to direct torque and is opposite in sign). 

The oscillating die rheometer (ODR) and the moving die rheometer (MDR) have been developed and maiketed by Monsanto, the MDR being introduced in 1985 [16]. In the MDR, a thin sheet of rubber, around 2 mm thick, is placed between the two dies kept at the desired temperature the lower disc oscillates and a reaction torque/ pressure transducer is positioned above the upper disc. It has been found that the MDR gives shorter times of cure than the ODR because of better heat transfer and higher torque values, owing to the die design. 

The 3-D ground reaction force vector, the vertical ground reaction torque and the point of application of the ground reaction force vector (i.e., center of pressure) are measured with force platforms embedded in the walkway. Force plates with typical measurement surface dimensions of 0.5 x 0.5 m are comprised of several strain gauges or piezoelectric sensor arrays rigidly mounted together. 

Fig. 15.25. Farinograph (according to Rohrlich and Thomas, 1967). The apparatus consists of a ther-mostated mixer or kneader (1), its blades are driven by an electromotor (2). The reaction torque acts through a lever system (4) of analytical balance precision on the indicator scale (5) simultaneously recorded on a strip chart recorder (6). The movement of the lever system is damped by an oil dash pot (3). The farinogram is a diagram of force versus time...

All the energy supplied to the fluid by the agitation system must eventually be dissipated as heat, so one possible method of measuring the power draw is to insulate the system and measure the temperature rise over time. In practice, this is extremely difficult to do accurately, due to problems with the effectiveness of the insulation and with the fluid physical properties being a function of temperature. Consequently, the method is rarely used, and methods based on measuring the reaction torque of the system are preferred. 

There are many methods available to measure the reaction torque. Some allow measurement of the individual torque contribution for each impeller (or any bearings, etc., in the system), while others can only be used to measure the entire system torque. Care should be taken with all methods to ensure that the true impeller torque can be isolated from any frictional torque loads applied by bearings and so on. 

Figure 4-10 Air bearing used to measure reaction torque.

If the reaction on the rolls appears halfway along the length marked /, as shown on the lower roll, the torque is... 

The dynamic compressors, axial and centrifugal, exhibit one other non-steady force, which is often questioned by foundation designers. This is the torque reaction force at the casing feet and, thus, the foundation due to surge. As a rule of thumb, a value of A the maximum steady-state torque reaction at the casing feet can be used. The frequency is the surge frequency, which is less than operating speed but not readily predictable, because it is heavily dependent on the connected system. 

One of the critical measurements is torque or shaft power. A variety of methods is recognized direct methods such as torque meters or reaction mounted drivers (dynamometers) and indirect methods such as electrical power input to drive motors, heat balance, or heat input to a loop cooler. See Part 7, Measurement of Shaft Power, PTC 19.7 1961 [3] for additional information. 

During the actual preparation of the GPC/SEC gel, there are several noteworthy items in the procedure. When combining aqueous and organic phases, always pour the organic phase into the water phase as the reverse procedure produces very large particles. This mixture must be held at 40°C to prevent the initiator from starting the reaction before the right size particles are formed. Rotor speed determines the particle size of the spheres the faster the speed the smaller the particles. Constant torque mixers produce the best results with more narrow particle-size distributions. The initial mixture should be stirred at 300-400 rpm to ensure a particle-size distribution from 2 to 20 yam. 

The kinetics of the reactive compatibilization of nylon-6-PP by acrylic acid modified PP was investigated by Dagli et al. [47]. The compatibilization reaction in this system involved the reaction between the acid group of acrylic acid modified PP and the amine group of nylon-6. A typical intensive batch mixer torque (t) vs time (t) trace for a ternary blend showing an increase in mixing torque upon the addition of PP-g-AA to a binary PP-NBR (85 7.5) blend is shown in Fig. 3. The kinetic... 

FIGURE 11.8 Torque time curves for two-step reaction. (From Naskar, M., Debnath, S.C., and Basu, D.K., Rubber Chem. TechnoL, 75, 309, 2002.)... 

The resultant force F is compensated by the reaction of the thread and, correspondingly, it does not influence the motion of the mass. In general, the total torque T has arbitrary direction, but we will be interested in only its vertical component, that causes a rotation in the horizontal plane. At the same time special measures are taken to remove an influence of motion in the vertical plane. 

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