Insertion meters

The insertion or Pitot turbine meter, a small turbine meter, is mounted on a probe in large (over 100 mm to 4 in.)-diameter pipe. The insertion meter... 

A few types of flowmeters measure the mass flow rate directly, but the majority measure the volumetric flow rate or the average fluid velocity, from which the volumetric flow rate can be calculated. To convert the volumetric rate to the mass flow rate requires that the fluid density under the operating conditions be known. Most meters operate on all the fluid in the pipe or channel and are known as full-bore meters. Others, called insertion meters, measure the flow rate, or more commonly the fluid velocity, at one point only. The total flow rate, however, can often be inferred with considerable accuracy from this single-point measurement. 

In this type of meter the sensing element, which is small compared to the size of the flow channel, is inserted into the flow stream. A few insertion meters measure the average flow velocity, but the majority measure the local velocity at one point only. The positioning of the sensing element is therefore important if the total flow rate is to be determined. The local measured velocity must bear a constant and known relationship to the average velocity of the fluid. 

OTHER INSERTION METERS. Modified forms of magnetic meters, turbine meters, ultrasonic meters, thermal mass flowmeters, and other types are available as insertion meters. They all have advantages for certain services. Insertion meters are generally cheaper than full-bore meters and are usually the most cost-effective method of measuring flow in large pipes. 

If compaction occurs as a result of production careful monitoring is required. The Ekofisk Field in the Norwegian North Sea made headlines when, as a result of hydrocarbon production, the pores of the fine-grained carbonate reservoir collapsed and the platforms on the seabed started to sink. The situation was later remedied by inserting steel sections into the platform legs. Compaction effects are also an issue in the Groningen gas field in Holland where subsidence in the order of one meter is expected at the surface. 

Extrusion. The filtered, preheated polymer solution is deHvered to the spinneret for extmsion at constant volume by accurate metering pumps. The spinnerets are of stainless steel or another suitable metal and may contain from thirteen to several hundred precision-made holes to provide a fiber of desired si2e and shape. AuxUiary filters are inserted in front of the fixture that holds the spinneret and in the spinneret itself to remove any residual particulate matter in the extmsion solution. 

Centering equipment is used to ensure that the impressed current anode is centrally situated in the borehole. The anode with the centering device can be inserted in the borehole by use of, for example, plastic-insulated wire ropes (see Fig. 9-11). After each of the anodes is inserted, the free space is filled with No. IV coke up to the level of the next anode about 50 kg of coke are necessary per meter of anode bed. The wire rope is fixed to a support above the borehole and provides offloading to the anode cable. The anode cables are laid to a junction box so that the... 

Turn the flow meter to the lower range and insert it in the side hole on the measuring tube to take readings. Move and turn the sensor slightly to be sure to get the highest reading. Record it. 

Any obstruction inserted into a duct or pipe that creates a measurable pressure difference can be used as a flow meter. The three basic standardized flow measurement devices presented above are perhaps more suitable for laboratory work than installation as permanent ductwork instruments in ventilation applications. They are sensitive to flow disturbances, relatively expensive, require considerable space, and have a narrow measurement range and a high permanent pressure loss. For these reasons, numerous attempts have been made to develop instruments without these drawbacks. Some of them, like the... 

The grade and quantity of product required were set on a meter. The driver inserted an authorization card and pressed the Start button. The required quantity was then delivered automatically. The filling arm had to be lowered before filling could start. 

By the use of suitable shunts, the basic moving-coil movement can be adapted to measure m almost unlimited range of currents. Figure 10.46 illustrates a direct-indicating instrument with shunt, to measure current up to 5 A d.c. To ensure that the resistance of the circuit is not materially altered by the insertion of an ammeter, it is usual to install either a shunt or the meter itself (usually a moving-coil meter with internal shunt) permanently in the circuit. Ammeter shunts are normally of the four-terminal type, to avoid contact resistance errors, i.e. two current terminals and two potential terminals, as shown, in fig. J0.46. 

Compact, ready-prepared calomel electrodes are available commercially and find wide application especially in conjunction with pH meters and ion-selective meters. A typical electrode is shown in Fig. 15.1(h). With time, the porous contact disc at the base of the electrode may become clogged, thus giving rise to a very high resistance. In some forms of the electrode the sintered disc may be removed and a new porous plate inserted, and in some modern electrodes an ion exchange membrane is incorporated in the lower part of the electrode which prevents any migration of mercury(I) ions to the sintered disc and thus... 

The Nernst equation shows that the glass electrode potential for a given pH value will be dependent upon the temperature of the solution. A pH meter, therefore, includes a biasing control so that the scale of the meter can be adjusted to correspond to the temperature of the solution under test. This may take the form of a manual control, calibrated in 0 C, and which is set to the temperature of the solution as determined with an ordinary mercury thermometer. In some instruments, arrangements are made for automatic temperature compensation by inserting a temperature probe (a resistance thermometer) into the solution, and the output from this is fed into the pH meter circuit. 

The flow rates of the two gases are regulated by flow meters inserted in parallel between the gas-mixing chamber and the chlorine and oxygen tanks. Appropriate flow rates for chlorine and oxygen are 80-100 and 40-50 ml. per minute, respectively. The checkers purchased gas flow meters from Arthur H. Thomas Company, Philadelphia, Pennsylvania. 

Glass pH electrodes are simple to use and maintain. They respond selectively to hydronium ion concentration and provide accurate measurements of pH values between about 0 and 10. They can be small enough to be implanted into blood vessels or even inserted into individual living cells. In precision work, these electrodes are calibrated before each use, because their characteristics change somewhat with time and exposure to solutions. The electrode is dipped into a buffer solution of known pH, and the meter is electronically adjusted until it reads the correct value. 

Is the patient hemodynamically stable If not, admit to the intensive care unit for ongoing treatment and monitoring. A PA catheter (or CVP catheter) should be inserted by trained medical personnel. Monitor PAOP to a goal pressure of 14 to 18 mm Hg and minimum cardiac index of 2.2 L/minute per square meter (alternatively CVP 8 to 15 cm H20). 

The simplest and most common device for measuring flow rate in a pipe is the orifice meter, illustrated in Fig. 10-7. This is an obstruction meter that consists of a plate with a hole in it that is inserted into the pipe, and the pressure drop across the plate is measured. The major difference between this device and the venturi and nozzle meters is the fact that the fluid stream leaving the orifice hole contracts to an area considerably smaller than that of the orifice hole itself. This is called the vena contracta, and it occurs because the fluid has considerable inward radial momentum as it converges into the orifice hole, which causes it to continue to flow inward for a distance downstream of the orifice before it starts to expand to fill the pipe. If the pipe diameter is D, the orifice diameter is d, and the diameter of the vena contracta is d2, the contraction ratio for the vena contracta is defined as Cc = A2/A0 = (d2/d)2. For highly turbulent flow, Cc 0.6. 

An orifice meter with a hole of 1 in. diameter is inserted into a l- in. sch 40 line carrying SAE 10 lube oil at 70°F (SG = 0.93). A manometer using water as the manometer fluid is used to measure the orifice pressure drop and reads 8 in. What is the flow rate of the oil, in gpm ... 

At the start of a casting operation, an explosion occurred when a metering rod was inserted into the tap hole to control the flow. Such rods are coated to prevent molten metal from sticking indications are that, in this case, the coating was not sufiRcientiy dry before use... 

The creamy suspension is allowed to cool to room temperature, and the electrodes of a pH meter are inserted (Note 4). A solution of 20.5 g. (0.15 mole) of zinc chloride (Note 5) in 75 ml. of water is added dropwise with vigorous stirring over a period of 45 minutes, while the pH is maintained at 7 by the simultaneous dropwise addition of a 4A aqueous solution of sodium hydroxide (Note 6). The mixture is stirred for 1 hour and is then filtered with suction the solid product is dried under reduced pressure over phosphorus pentoxide. The dry material is slurried with 200 ml. of petroleum ether (b.p. 30-60°), and the solvent is decanted. This process is repeated five times, and the combined extract is evaporated at reduced pressure. The yield of almost pure -chlorophenyl isothiocyanate, obtained as a readily crystallizing oil with a pleasant anise-like odor, is 33-35 g. (65-68%), m.p. 44-45°. The product can be recrystallized from the minimum amount of ethanol at 50°. 

Insert the pH probe into the KHP solution. When the pH meter is stable, press TRIGGER on the CBL unit. 

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