Performance of pressure control valves and flow meters precision in operational irrigation-water balance accuracy

In pressure irrigation-water distribution networks, pressure regulating devices for controlling the discharged flow rate by irrigation units are needed due to the variability of flow rate. In addition, applied water volume is used controlled operating the valve during a calculated time interval, and assuming constant flow rate. In general, a pressure regulating valve PRV is the commonly used pressure regulating device in a hydrant, which, also, executes the open and close function. A hydrant feeds several irrigation units, requiring a wide range in flow rate. In addition, some flow meters are also available, one as a component of the hydrant and the rest are placed downstream. Every land owner has one flow meter for each group of field plots downstream the hydrant. Its lecture could be used for refining the water balance but its accuracy must be taken into account. Ideal PRV performance would maintain a constant downstream pressure. However, the true performance depends on both upstream pressure and the discharged flow rate. The objective of this work is to asses the influence of the performance on the applied volume during the whole irrigation events in a year. The results of the study have been obtained introducing the flow rate into a PRV model. Variations on flow rate are simulated by taking into account the consequences of variations on climate conditions and also decisions in irrigation operation, such us duration and frequency application. The model comprises continuity, dynamic and energy equations of the components of the PRV.

Chamber of valves in the Arenoso reservoir

Of the south of Spain, near the province of Cordova, in a tributary of the Guadalquivir River it has been constructed during the years 2004 to 2007 the reservoir called El Arenoso. El Arenoso reservoir that belongs to Environment Ministry is destined to downstream Guadalquivir’s water supply and the general regulation of the river. The dam is located on the same name river and it is next to the Montoro’s municipal district, 41 km northeast of Cordova. The main work consists on an embankment dam, with central clay core, and slates and greywacke shoulders. The core is covered downstream with a filter material and upstream with a transition material. The dimensions of the dam are 80 m high, 1.480 m long at its crest, and it has been needed more than 3 million m3 of materials, creating a waterproof barrier able to keep 160 hm3 as a useful reservoir. In the zone of the core is located the chamber of valves with a horizontal clearance of 10 m and a vertical clearance of 14,517 m. The present article exposes the most important characteristics of project and construction, of valves chamber of the Arenoso reservoir.

Ballistic spin-valves with Ni nanocontacts

Poster presented in TNT 2005 "Trends in Nanotechnology", Oviedo, Spain, 29 August-02 September, 2005.

Slide valve gears : an explanation of the action and construction of plain and cut-off slide valves /

Includes index.

Liquid rocket pressure regulators, relief valves, check valves, burst disks, and explosive valves.

Cover title.

The development of high-head outlet valves /

Mode of access: Internet.

Study of gate valves and globe valves as flow regulators for irrigation distribution systems under heads up to about 125 feet of water /

Mode of access: Internet.

The steam fitters' computation and price book; consisting of tables giving the cubical contents of rooms of various sizes, tables giving the number of square feet of wall surface, tables giving the number of square feet of window surface. Tables giving radiation required for rooms of any size at various proportions. Also tables showing the cost of radiation ... Tables giving size, price, weight etc., of pipe, fittings, valves, etc. In addition ... some general information on points of interest to steam and hot water fitters.

At foot of t.-p.: Copyrighted 1893 by Mark Dean; on verso of t.-p. copyright date given 1895.

Link motions, valve gears and valve setting : a practical treatise which explains the mysteries of valve setting. Shows the different valve gears in use, how they work and why. Piston and slide valves of different types and illustrated and explained /

Mode of access: Internet.

Hydraulic experiments with valves, orifices, hose, nozzles, and orifice buckets.

Mode of access: Internet.

Valves and valve-gearing : a practical text-book for the use of engineers, draughtsmen, and students.

Mode of access: Internet.

Fairbanks valves ... illustrated catalogue and price list

Mode of access: Internet.