Pressure indicator

In some cases when drilling fluids invade a very low permeability zone, pressure equalisation in the formation can take a considerable time. The pressure recorded by the tool will then be close to the pressure of the mud and much higher than the true formation pressure. This is known as supercharging. Supercharging pressures indicate tight formation, but are not useful in establishing the true fluid pressure gradient. 

Reservoir pressure is measured in selected wells using either permanent or nonpermanent bottom hole pressure gauges or wireline tools in new wells (RFT, MDT, see Section 5.3.5) to determine the profile of the pressure depletion in the reservoir. The pressures indicate the continuity of the reservoir, and the connectivity of sand layers and are used in material balance calculations and in the reservoir simulation model to confirm the volume of the fluids in the reservoir and the natural influx of water from the aquifer. The following example shows an RFT pressure plot from a development well in a field which has been producing for some time. 

AH values relate to defined conditions, usually to the standard state of the substance at 298 K and 1 atm pressure, indicated by AH%i,. That is. 

Disclosing waxes or pressure indicating pastes, are used in fitting a dental appHance to estabhsh the location and extent of high spots or pressure areas, as on impressions and complete dentures. They are very soft, salve-like compositions that are painted onto the tissue side of an impression or denture. When the wax-coated denture is seated in the mouth, the soft paste is forced out of the areas showing hard contact between the denture and the mucous membrane. These areas on the denture can be easily marked and material removed from the denture to reheve the premature or hard contact. 

Seal legs are frequently used in conjunction with solids-flow-control valves to equ ize pressures and to strip trapped or adsorbed gases from the sohds. The operation of a seal leg is shown schemati-caUy in Fig. 17-19. The sohds settle by gravity from the fluidized bed into the seal leg or standpipe. Seal and/or stripping gas is introduced near the bottom of the leg. This gas flows both upward and downward. Pressures indicated in the ihustratiou have no absolute value but are only relative. The legs are designed for either fluidized or settled solids. 

Vahdation of the measurements may require the simultaneous measurement of pressure and temperature. Typical sample locations do not have thermowells and pressure indicators. Consequently, modifications will be reqmred to facilitate validation. 

Lines are not Follow operating procedures depressurized, Install pressure indication instrumentation and before checking, changing filters. CCPS G-3 CCPS G-22 CCPS G-23 CCPS G-29... 

Heat build-up Replace screen with one correctly sized and/or due to too fine or clean screen blocked outlet, Install pressure indicator downstream and screen. upstream of mill for conveyed systems Measure temperature at strategic points in mill casing to detect and alarm product temperature rise CCPS G-12 CCPS G-23 CCPS G-29... 

High pressure Low/no flow - chlorine gas supply line for bleaching line A (linked from 5.2) High temperature (linked from 4.3) High pressure - chlorine railcar (linked to 1.5) Potential damage to the vaporizer if isolated from the relief valve on the chlorine railcar (linked to 4.9) Local pressure indication ... 

Figure 10-9. Pressure indicator piping arrangements taken from a field test where only two sets of instruments could physically be installed.

Pressure indicators are specified to aid in making adjustments and in evaluating burner performance. Water manometers may be used in this service, but must be shut off when not in use. 

V.ilve too [iitemai f.iilijf d Operation High Nj pressure at HF cylinders, HF vaporizer vessel rupture - HF released to atmosphere Local pressure indication on N, line PRV-3 nt V- i / nutlcl 11 If N - line relic valwh lot, vapori/cr relief valve should not lift. 

Valve cin vil loo tai [iiloni-il valve failure Operation No Ny pressure to HF cylinder - no HF flow Lo vaporizer, B-l wing Local pressure indication on N2 line None tv ... 

If severe, same as valve closed too far Local pressure indication on Nj line, if severe ... 

The safety valve through which MIC escaped was redundant with an unmonitored graphite upSure disk. Checking it required manual inspection of a pressure indicator located between the disk and the safety valve. 

Rupture discs are also used below relief valves to protect them from corrosion due to ves.sel fluids. The rupture disc bursts first and the relief valve immediately opens. The relief valve reseals, limiting flow when the pressure declines. When this configuration is used, it is necessary to monitor the pressure in the space between the rupture disk and the relief valve, either with a pressure indicator or a high pressure switch. Othei-wise, if a pinhole leak develops in the rupture disk, the pressure would equalize on both sides, and the rupture disk would not rupture at its set pressure because it works on differential pressure. 

Vent and purge lines Procedure to indicate how to check if fully purged Ensure training covers symptoms of pressure in line Line pressure indicator at controls. Interlock device on line pressure. 

During the separation itself some trouble can occur concerning the back pressure. An increasing back pressure indicates contamination of the column and thus should be monitored. If this happens or if a visible contamination of the sorbent is noticed, a regeneration of the column is necessary. However, if the back pressure rises very rapidly the column may be clogged by denatured proteins. As a first attempt, the frits should be replaced by new ones, trying the top adapter first. 

GPLA Glycol system pressure indicator fails... 

This chart is applicable only to flammable liquids or gases in equilibrium In a closed container. Mixtures of vapor and air will be too lean to burn at temperatures below and at pressures above the values shown by the line on the chart for any substance. Conditions represented by points to the left of and above the respective lines are accordingly nonflammable. Points where the diagonal lines cross the zero gauge pressure line (760 mm of mercury absolute pressure) indicate flash point temperatures at normal atmospheric pressure. 

Upon shutting in the well, the pressure builds up both on the drillpipe and casing sides. The rate of pressure buildup and time required for stabilization depend upon formation fluid type, formation properties, initial differential pressure and drilling fluid properties. In Ref. [143] technique is provided for determining the shut-in pressures if the drillpipe pressure is recorded as a function of time. Here we assume that after a relatively short time the conditions are stabilized. At this time we record the shut-in drillpipe pressure (SIDPP) and the shut-in casing pressure (SICP). A small difference between their pressures indicates liquid kick (oil, saltwater) while a large difference is evidence of gas influx. This is true for the same kick size (pit gain). 

Fluctuations in the inlet and discharge pressures indicate potential system problems that may adversely affect performance and reliability. Pressure fluctuations are generally caused by changes in the ambient environment, turbulent flow, or restrictions caused by partially blocked inlet filters. Any of these problems will result in performance and reliability problems if not corrected. 

If the unit pressure balance indicates that either the pressure gain in the standpipes is inadequate or the delta P across the slide valves is erratic, standpipe aeration and instrumentation should be examined. Redesigning the aeration systems or replacing the standpipes can gain valuable pressure drop. Proper instrumentation can include independent aeration flow to each tap, flow indicators/controllers on each, and differential pressure indicators between the taps. 

Since excess pressure indicates malfunction of part of the system - usually a condenser fault or incorrect closure of a valve - the high-pressure switch should be reset manually, not automatically. 

The range of total pressure indicated in the graph corresponds to the lowest value at which the condensation of H20/dioxane vapors is feasible by using cooling water at a maximum temperature of 35°C (as in when using water from the cooling tower), namely, without the extra cost of energy for the eventual production of chilled water. 

It may be noted that the pressure measuring devices (a) to (e) all measure a pressure difference AP(— Pj — P ). In the case of the Bourdon gauge (0, the pressure indicated is the difference between that communicated by the system to the tube and the external (ambient) pressure, and this is usually referred to as the gauge pressure. It is then necessary to add on the ambient pressure in order to obtain the (absolute) pressure. Even the mercury barometer measures, not atmospheric pressure, but the difference between atmospheric pressure and the vapour pressure of mercury which, of course, is negligible. Gauge pressures are not. however, used in the SI System of units. 

Hot pressing requires a refractory die, pressure and heat sources and temperature- and pressure-indicating devices. For many applications the die containing the sample to be hot pressed is heated either by a separate furnace (for < 1000°C) or by inductive or resistance heating of the die body itself. Uniaxial pressure is applied through the ram of a hydraulic or pneumatic press. 

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