Expansion tanks

If the back pressure on the outlet side of the compressor is below the fixed output pressure, the compressed gas will simply expand in an expansion tank or in the initial portion of the pipeline attached to the outlet side of the compressor. Figure 3-74 shows the pressure versus volume plot for a typical rotary compressor operating against a back pressure below the design pressure of the compressor. 

LTHW systems are usually under a pressure of static head only, with an open expansion tank, in which case the design operating temperature should not exceed 83°C. Where MTHW systems operating above 110°C are pressurized by means of a head tank, an expansion vessel should be incorporated into the feed and expansion pipe. This vessel should be adequately sized to take the volume of expansion of the whole system so that boiling will not occur in the upper part of the feed pipe. On no account should an open vent be provided for this type of system. MTHW and HTHW systems require pressurization such that the saturation temperature at operating pressure at all points in the circuit exceeds the maximum system flow temperature required. A margin of 17 K (minimum)... 

Figure 7.6 Dry expansion tank evaporator, (a) Section, (b) Elevation...

The preferred brine circuit is that shown in Figure 12.5, and having the feed and expansion tank out of the circuit, which is otherwise closed. This avoids entrainment of air and too much surface exposure. The same arrangement can be used with the divided storage tank shown in Figure 12.6, except that the tank will be enclosed, with a separate feed and expansion tank. 

Check the expansion tank. If it is full of water, there is likely to be insufficient air space for expansion and the relief valve will open. 

The pressure in the borehole can be reduced by having a tube of elastic material filled with silicone oil. When a slight overpressure due to the freezing occurs the silicone oil will be pressed away to an expansion tank, see Figure 64. 

Figure 64. The pressure from the freezing will be taken care of by the silicone oil and regulated by an expansion tank...

Heat Cable in the Borehole Connected to an Expansion Tank By inserting a heat cable in the borehole it is possible to prevent the overpressure, see Figure 66. The heat cable should be connected to the brine expansion tank. When the expansion of freezing water increases the volume in the expansion tank the heating starts, which makes it possible to always have a drainage hole though the ice. 

Inspect hoses. Tighten all hose connections, including those to the expansion tank, to protect against coolant loss. 

The minimum size of the hot oil storage tanks (T1 and T2) is based on the requirement to provide energy for one night, though preferably it should be for several days of unfavorable weather conditions. The hot oil system is a closed one, and an expansion tank is provided (not shown) to accommodate the thermal expansion as the oil temperature changes. Until a storage tank is full of hot oil, the temperature rises with the level in the tank and, therefore, the cold oil is taken from and returned to the bottom of the active tank, while the hot oil is taken from and returned to the top of the tank. 

Note the chlorine gas detector. The liquid chlorine is under pressure and could break pipe connections, so the location at the container section is appropriate. Also note the expansion tank and the rupture disk. Again, because the liquid chlorine is under a very high pressure, any leakage that may occur in the piping may be stopped by rupturing the disk and allowing the chlorine to expand into the expansion tank. 

Sudden expansion (tank inlet) Gate valve 1.0 50... 

In the startup of a process, Dowtherm, an organic liquid with a very low vapor pressure, was being heated from room temperature to 335 F. The operator suddenly noticed that the gauge pressure was not the expected 15 psig but instead was 125 psig. Fortunately, a relief valve in the exit line ruptured into a vent (expansion) tank so that a serious accident was avoided. 

Separators and Catchalls.—To prevent losses by entrainment or foaming, it is necessary to install efficient separators and catchalls. For ordinary conditions, standard so-called oil separators" with baffle plates may be us, but for extreme cases, separators of the centrifugal t3q>e, or very large expansion tanks with baffles must be mstalled. Prof. E. W. Kerr has given the results of some tests made with a Swartwout separator, which has shown extremely high efficiency (See Bull 138 and 149 of the Louisiana State University). 

The most important property for a high-temperature HTF is its thermal stability at exceptionally high temperatures. These HTFs are normally used above their flash and fire points in closed and airtight systems. In many applications, an inert gas such as nitrogen is utilized in the head space of the holding/ expansion tank. 

Organic HTFs oxidize when heated in the presence of air. This starts at about 150°C and the rate increases with temperature. Heat transfer fluid manufacturers usually recommend a blanket of an inert gas such as nitrogen or argon on the expansion tank to prevent oxidation. This inert gas can also be utilized to pressurize the system in case the fluid will be utilized above its boiling point or the net positive suction head (NPSH) of the pump needs to be elevated. 

Flow of the HTF through the expansion tank during start-up is recommended because it facilitates venting... 

The extraction of the mechanical power has an influence on the chemical reactivity as well, by controlling the pressure in the HYPP components. Provisions like safety valves, expansion tanks, flarestacks, can be foreseen in order to release the pressure, thus avoiding the failure of equipments... 

Major polymer applications appliances, automotive (doorhandles, window winders, tank filler necks and caps, carburetor, screw caps for cooling system expansion tanks, fuel piunps) phones (diahng units and slider guideways), pneumatic components, parts of textile machines, shower parts, home electronics and hardware, bearings, cams, containers, pump impellers, rollers, springs, clips, and many other applications... 

An overflow pipe delivers a small amount of the circulating liquor into the open expansion tank at the side. This is necessary because, under working conditions, the pressurized compartment must be completely filled with dye liquor and some accommodation for the increase in volume which accompanies the rise in temperature is therefore essential. It also provides a convenient point at which dyes and chemicals can be added. At the commencement of dyeing the flow should always be from outside to inside and, after a-few minutes, the intermittent reversal in direction may be set in motion. 

The arrival of hydrophobic synthetic fibres created interest in dyeing, under pressure, at temperatures above 100°C. The machine illustrated in Fig. 13.16 has a secondary pump which is brought into operation to create a static high pressure in the d e vessel when it is desired to apply the dyes at temperatures above 100°C. A constant elevated pressure cannot be maintained satisfactorily by the main pump alone because it would vary according to tbe density of the winding of the padcages and other factors, including the speed of the motor. The secondary pump extracts extra dye liquor from the expansion tank and introduces it into the pressure vessel in such a manner that a static pressure is maintained. 

The simplest continuous evaporation system is the single stage flashing of a heated liquid into an expansion tank orflash which is maintained... 

The DAVINCH is a double-walled steel chamber. The replaceable inner vessel is made of armor steel and the outer vessel is made of multilayered carbon steel plates with a corrosion- and stress-crack-resistant inner plate made of, for example, stainless steel, Hastalloy, or a similar material. The chambers are separated by air. Owing to its double-wall design and the materials of construction, the DAVINCH has the ability to confine high-pressure detonation gases, eliminating the need for an expansion tank to contain them following a detonation. 

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