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Cold water services
Published in Derek Worthing, Nigel Dann, Roger Heath, of Houses, 2021
Derek Worthing, Nigel Dann, Roger Heath
For maintenance purposes, stopcocks or stop valves (also known as service valves) are used to isolate parts of the pipework. These should be located as near as possible to the appliance which they serve and should obviously be easily accessible. It is also good practice to label these devices to indicate which parts of the installation they serve. In addition, a stopcock (or valve) and drain cock should be fitted just above the point where the rising main enters the house. In many cases, the service pipe will enter the building below a sink unit and Figure 20.6 shows a typical arrangement of the hot and cold pipework. The pipes have yet to be earth bonded (see Chapter 24).
Prevention: Design and Construction Considerations
Published in Stuart A. Smith, MONITORING and REMEDIATION WELLS, 2017
If maintenance and reliable operation are major concerns in the project being planned, bailers dedicated to individual wells have many advantages. Bailers have no moving parts aside from balls and stopcock valves. They require no power transmission via air line or cable and are not prone to clogging in routine use. Stopcocks and check valves may block open or closed with silt or sand.
Effect of nanoscale zero-valent iron on the change of sludge anaerobic digestion process
Published in Environmental Technology, 2020
Jun Zhou, Xiaogang You, Tongtong Jia, Baowei Niu, Lei Gong, Xiaoqi Yang, Ying Zhou
NZVI was prepared by liquid phase reduction [26]. Deionized water and 0.2% (w/w) sodium carboxyl methyl cellulose (CMC) solution were purged with high purity nitrogen for twenty minutes before use. Then 50 mL of 0.625 M ferrous chloride was gradually added to 200 mL of 0.2% CMC solution under nitrogen gas purging. Finally, 100 mL of 1.5% (w/w) sodium borohydride (NaBH4, Sigma) was added drop wise to the solution while the solution was stirred. The NZVI stock solution was purged with nitrogen gas throughout the synthesis process to ensure that only NZVI was formed. The NZVI particles had an average size of 50–70 nm [27]. The batch experiments were undertaken in 500 mL (300 mL substrate and 200 mL inoculum) glass bottles. Each reactor consisted of 3 stopcock valves, used for collecting biogas, sludge and purging N2 gas at the beginning of the digestion period, respectively. The concentration of NZVI in the experimental group was 1000 mg/L, while the blank group without any NZVI. All the reactors were performed in triplicate and kept in a water bath at 35°C to maintain mesophilic conditions.
Glove permeation of chemicals: The state of the art of current practice, Part 1: Basics and the permeation standards
Published in Journal of Occupational and Environmental Hygiene, 2019
The ASTM F739 standard for continuous contact was issued in 1981[16] based on Nelson et al.[23] Revisions were made in 1985, 1991, 1996, 1999, and 2012.[16,24] Two polytetrafluoroethylene (PTFE) gaskets hold the glove material specimen vertically between glass challenge and collection chambers (Figures 1 and 2).[16] The 2012 primary cell allows a material exposure/collection diameter of 2.54 cm (Figure 1) and the alternative cell material exposure diameter is 5.1 cm (Figure 2). Both have filling/sampling tubes and optional stopcock valves to facilitate different collection side configurations or continuous or static liquid challenges at 27 ± 1 °C. It might be noted that previous versions of ASTM F739 did not mention a standard temperature but did specify a user temperature variation of no greater than ±1 °C. The 2012 standard does allow other temperatures to be used.
Study on Foaming Properties of Polyoxyethylene Alkyl Ether Carboxylic Salts with Different Structures
Published in Journal of Dispersion Science and Technology, 2011
Xin-Wang Song, Lei Zhang, Xiao-Chun Wang, Lu Zhang, Sui Zhao, Jia-Yong Yu
The surfactant solution (50 mL) is poured into a glass cylinder (500 mL) with a fritted glass G-2 disc at the bottom, with a syringe attached to the bottom by means of a stopcock.[20] Gas is introduced manually via the syringe and stopcock, the constant gas rate (10 mL · s−1) is controlled by using a peristaltic pump, in a fixed time (20 seconds), into the bottom of the column and the stopcock closed. The parameter of foaming ability, Rv, is expressed as[21]: where Vfoam is the initial volume of the foam generated, t is the introduction time of gas and s is the gas rate. The time for reducing the initially produced foam by half (the so-called “half-time”), t1/2, is recorded.