Gauge consistency

For measuring pressures of corrosive fluids, slurries, and similar process fluids which may foul Bourdon tubes, a cfiemical gauge, consisting of a Bourdon gauge equipped with an appropriate flexible diaphragm to seal off the process fluid, may be used. The combined volume of the tube and the connection between the diaphragm and the tube is filled with an inert liquid. These gauges are availabTe commercially. 

The spiral gauge consists of a hollow spiral of very thin glass or quartz fixed at the end at which it is connected to the vacuum line, the other end being closed. Changes in the difference between inside and outside pressure lead to expansion or contraction of the spiral. The resulting movement can be magnified by a mechanical or optical lever. 

Thermal Conductivity Vacuum Gauges. A very widely applied gauge of this type is the Pirani gauge. Such gauges consist of a wire (Pt, W or Ni, d = 5-20 pm / 5 cm) mounted axially in a cylindrical tube (d 2 cm). The wire is heated by an electric current to approximately 100°C above the ambient temperature and heat loss occurs by three mechanisms, as indicated in Figure 5.3. 

The Wrede—Harteck gauge consists of a small chamber in communication with the atom—molecule mixture via a hole whose dimensions are small compared with the mean free path. The chamber is coated with an efficient catalyst so that, ideally, every atom which enters is recombined. Because the atom flux is unidirectional, a pressure difference (AP) between the pressure outside and inside the gauge will characterise the stationary condition, such that... 

The Bourdon gauge consists of a flattened, thin-walled metal tube bent into the form of an arc or C shape as illustrated in Figures 4.7 and 4.8 [3]. One end of the tube is fixed and securely sealed and bonded to a threaded connection called a socket. The other end is tightly sealed and free to move. At atmospheric pressure (zero gauge pressure) the tube is undeflected and for this condition the gauge pointer is calibrated to read zero pressure [4]. However, when pressure is applied into the fixed end of the tube, the effect of the forces tends... 

The McLeod gauge consists of a finely calibrated capillary tube attached to a large spherical bulb whose volume, Vb, is known precisely. The base of the bulb is connected to both a reservoir of mercury as well as a reference... 

Optical Properties The optical values of Equistar Chemicals NA 345 actually improve with decreases in film gauge and are maintained at wide die-gap settings, leading to cost savings. Film can be drawn down to a minimum gauge consistent with required physical properties. With wider die-gaps, back pressures are reduced, as are extrusion costs. 

LLDPE has become a key PO for blown film, but not without some difficulties in establishing methods for maintaining bubble stability and gauge consistency. Typically, LDPE is blended with the LLDPE to inaease melt strength and bubble stability, but this can reduce tensile tear, and dart-impact strengths. Alternatively, process developers have turned their attention to a melt-strength additive (MSA) developed by DuPont Canada in the 1980s particularly for when bubble stability is a problem. 

Bourdon gauge A pressure gauge consisting essentially of a C- shaped or spiral tube with an oval cross section. One end of the tube is connected to the fluid whose pressure is to be measured and the other end is sealed. As the pressure inside the tube is increased, the oval tube tends to become circular and this causes the tube to straighten. The movement of the end of the tube is... 

The electrical resistance strain gauge method is the most popular and widely accepted method for strain measurements. The strain gauge consists of a grid of strain-sensitive... 

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