Valve boxes

In the cathodic protection of storage tanks, potentials should be measured in at least three places, i.e., at each end and at the top of the cover [16]. Widely different polarized areas arise due to the small distance which is normally the case between the impressed current anodes and the tank. Since such tanks are often buried under asphalt, it is recommended that permanent reference electrodes or fixed measuring points (plastic tubes under valve boxes) be installed. These should be located in areas not easily accessible to the cathodic protection current, for example between two tanks or between the tank wall and foundations. Since storage tanks usually have several anodes located near the tank, equalizing currents can flow between the differently loaded anodes on switching off the protection system and thus falsify the potential measurement. In such cases the anodes should be separated. 

Insulation formed by slurry casting or heat curing under pressure in molds in a number of insulation types. Most common moldings are preformed bends, valve boxes and flange covers. 

All pipework must be installed to the appropriate standard and codes of practice. The degree of insulation will be suitable for the temperature of the pipework, although the finish may vary, depending upon site preferences. Valve boxes are recommended, although on some low-pressure installations these are not always included. 

Steam transmission will produce noise. Low steam velocity will help to reduce this. One specific noise area will be if a pressure-reducing valve set is employed. Therefore it is desirable to have this within the boiler house or other building and not outside. Some types of pressure-reducing valves operate at lower sound levels than others, and therefore if environmental noise could be a problem then this should be investigated. Insulated valve boxes will also help to contain any noise. 

Valves, the use of which may be necessary for the safe operation of a hydrogen distribution system, shall be checked and serviced, including lubrication where necessary, at sufficiently frequent intervals to assure their satisfactory operation. Examination shall include checking of alignment to permit use of a key or wrench and clearing from the valve box or vault any debris that would interfere with or delay the operation of the valve. Valves in hydrogen service shall be checked and serviced at least annually. 

VII-3.3.3 Utilization. Good judgment shall be used to determine when available openings (such as manholes, vaults, or valve boxes) are sufficient to provide an adequate survey. When necessary, additional sample points (bar holes) shall be made. Sampling points shall be of sufficient depth to sample directly within the subsurface or substructure atmosphere. 

Move as quickly as possible with the most obvious and cost-effective physical improvements, such as perimeter fences, security lighting, tamper-proof manhole covers and valve boxes, etc. 

Many of these lockout devices are not specifically designed for use in the chemical industry (e.g., chains, padlocks) and are available from a local hardware store or manufacturer specializing in safety equipment. Other lockout devices (for example, valve-specific lockouts or valve box-locks) are more specialized and must be purchased from safety or valve-related equipment vendors. 

As shown in Fig. 1, polishers are typically connected to a global delivery piping system by a valve box. The valve box enables polishers to be added or removed from the global system without shutting down the entire system... 

Fig. 5. Valve boxes for global slurry delivery system.

Untreated silica column can be advantageously used for HPLC preseparation of PAHs from triglycerides. The capacity of a silica column to retain fat (for columns of the same particle size) depends on the column size, the mobile phase composition, as well as the type and by-products (free acids and polymerized material) of the fat injected [706,713]. Off-line HPLC-HPLC, employing silica column (250 X 4.6 mm i.d., 5 pm of particle size) for sample preparation before RP-HPLC and spec-trofluorometric detection, was successfully applied for PAH determination in edible oils [659,691] and fish [714]. After PAH elution, the silica column needs to be backflushed with dichloromethane to remove the fat. The entire sample preparation step can be automated by using a backflush valve and a programmable switching valve box [691]. 

CATION OR ANION UNIT TO BE PREASSEMBLED ON A STRUCTURAL STEEL SKID, WITH EQUIPMENT TUBED AND/OR WIRED TO THE SOLENOID VALVE BOX. SUBJECT TO SHIPPING CLEARANCES, MORE THAN ONE VESSEL CAN BE MOUNTED ON A COMMON SKID-CONDUCTIVITY INSTRUMENT AND CELL USUALLY NOT FURNISHED FOR CATION UNITS. (REFER TO DATA SHEETS). 

Hiac ChemQual on line sampler is designed to provide a solution for the connection of a particle sensor to bulk chemical distribution systems and distribution valve boxes for pre-hookup qualification. A built-in air pump eliminates the need for an external gas supply for enclosure and line purging. For continuous monitoring applications, the sampler is also compatible with Particle Vision Online facility monitoring software. The light source is a laser diode with count display at 4 channels 0.1, 0.2, 0.3, 0.5 pm at a flow rate of 100 ml min f... 

Fig. 31. Apparatus for the study of oxygen exchange with a circulation system. 1, reaction vessel 2, circulation pump 3, valve box 4, cold traps 5, gas sampling ampoule 6, cold trap 1, mano-metric valves 8 to 12, gas storage bulbs 14, gas burette 16, adsorption vessel 24, oxygen purification system. From ref. 245.

Most of the system interlocks are handled by the embedded NI controller. This is similar to that used in other laboratory-scale reactor systems (Mills and Nicole, 2005) except the Siemens 545 PLCs have been replaced with the National Instruments system. The National Instruments controller monitors the status of the AIMS process variables and takes appropriate action if any interlock conditions are found. In addition to these interlocks, the external heater controllers that are used for the system heating tapes and sampling valve box contain hardwired overtemperature interlocks built-in to these controllers. However, these interlocks only interrupt power to the affected heating device, so the NI controller must still take action to shutdown the rest of the process. 

Valve boxes for underground pipelines should have side walls only. Box drainage should be through a gravel bed at the open bottom of the valve box. 

Trapped headspace volatiles were thermally desoibed with a Dynathom Thermal Desorption Unit (TDU) ACEM 900. The narrow bore focusing tr q> was packed with a two-part bed consisting of Toiax TA and Carboxoi 1000. limes and temperatures for desorption woe 10 min. dry, 3 min. soibait tube heat at 235 °C, 3 min. focusing trap heat at 235 °C, valve box and transfer line temperatures at 235 C. 

Another t) e of enclosure that is often used is the small valve box, often installed near the point of use. This box, usually constructed of steel, may contain one or more regulators or valves and provides an increased level of safety should the local distribution components contained inside the box fail. 

Avoiding bending and stress in a pipe system is a factor in the installation of plastic pipe. Unlike steel pipe, plastic pipe is not intended to support heavier weights, such as valves, anchors, and so forth. Plastic pipe is designed to support soil loads and internal pressnres up to a specified hydrostatic pressure rating. When accessories are placed in the pipeline, such as valve boxes, the accessories must be supported to prevent additional bending and stress on the plastic pipe. 

Check the site for evidence of substructures such as manhole covers, valve box covers, meter boxes, electrical transformers, conduits or drop lines from utility poles, and pavement patches. HDD may be a suitable method in areas where the substracture density is relatively high... 

Level C Adds aboveground survey data (such as manholes, valve boxes, posts, and... 

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