S & A Produce (UK) Ltd, a major producer of soft fruit under glass, has recently upgraded its pumping equipment for irrigation and overhead moisture. In addition to the new pumps, all the main pumps at the site have now been equipped with a computer-controlled variable speed drive. This much finer control of pumping operations has contributed to higher yields and quality and has eliminated damaging pipe bursts.
The company is the largest privately owned soft fruit grower/packer in the UK, producing 800010000tons annually and employing around 2000pickers. Its main site is Brook Farm, Marden near Hereford. This is an open-air market garden where the bulk of the company's crop is produced during the UK's growing season. In 2002 S&A purchased Hernhill Nursery, near Faversham in Kent to produce winter and spring crops under glass.
Jason Lewis, General Manager of Hernhill Nursery explains: “We took over 15hectares of green housing here which was originally used to produce tomatoes. We now use it to grow 1600 to 1800tons of strawberries and raspberries per year and employ around 400pickers. We have two annual crops one running from end of September to January and the other from mid-March to end of June/July.“
The plants are grown hydroponically in raised toughs containing peat. “We try to control the growing environment as much as possible,“ says Jason Lewis. “The temperature is kept between 14to18oC, additional carbon-dioxide is pumped in when needed, overhead moisture is provided by sprayers, sprinklers and misters and we have 140 520metres of piping supplying irrigation. All of this monitored and controlled by computer.“
“We took over the basic equipment from the nursery's tomato-growing days,“ says John Fuller, Maintenance Manager, “except for the growing troughs and over-head moisture system, which S&A installed and we've now recently up-graded the irrigation system. This upgrade consisted mainly of installing new pumping equipment: we originally had four, 11 kW, Lowara SV6004F110T pumps in the irrigation pump station. We've now moved these to the aoverhead' pump station (which supplies the sprayers, sprinklers and misters) and equipped them with pump-top Hydrovar units. The irrigation pump station is now equipped with seven new 18.5kW, Lowara SV9203/2F185T pumps, also with pump-top Hydrovar units.“
Increased irrigation capacity
“The irrigation pipes are of 110mm (ca 4-in) diameter,“ comments Roger Burt of Autometric Pumps (a division of Mid-Kent Electrical Engineering Co Ltd), who sold the new pumping equipment to Hernhill Nursery. The equipment was commissioned on site by Lowara. “The new set up in the irrigation pump station increase capacity by 30to50percent and also increases reliability; the seven pumps share and rotate pump duties and should one of them fail, a valve system enables it to be by-passed until it's fixed or replaced. In addition, the pressure in the pipes varied from 7to10 bar. Hydrovar now limits it to 4.5bar, making their problem with pipe burst a thing of the past.“
“Hydrovar is a variable speed drive whose software has been pre-programmed for the sole purpose of centrifugal pump operation,“ explains Ian Dure, Lowara UK's Southern Region Manager. “It's this dedicated software which differentiates the Hydrovar from other Variable Frequency Drives (VFD) available in the market today. Hydrovar's single purpose programming results in simplified installation and set-up while at the same time provides greater pump control capabilities resulting in improved pumping system reliability. The customer benefits include: reduced energy consumption Hydrovar eliminates the need for pump throttling by regulating pump speed and output to match demand thereby eliminating wasted energy traditionally aburnt-off' across the control valve.
Typically a 3050percent energy reduction can be realised which in many cases means that the energy savings will pay for the cost of the Hydrovar unit in less than one year!
“Increased pump reliability and decreased maintenance costs because the Hydrovar software can be set-up to protect the pump from operating under unfavourable conditions. Hydrovar can be provided with min and max set points, which are used to maintain pump performance within the recommended operating range of the pump.
If conditions prevail where demand requires pump operation outside these limits, Hydrovar will automatically shut down the pump and send an alarm. This capability prevents the pump from adead heading' or being run off the curve; both conditions know to reduce seal and bearing life and sometime result in catastrophic failure. Similarly if changes in suction conditions (eg, draining of a vessel, etc) were to result in cavitation or dry running, again Hydrovar will shut down and alarm thereby protecting both the pump and its shaft seal from failure. Unlike other VFDs on the market today the ability to shutdown the pump and prevent dead-heading, dry running, cavitation or running the pumps aoff the curve' is unique only to Hydrovar and results in increased pump reliability and decreased maintenance cost.“
As regards the advantages of equipping Hernhill Nursery's pumps with Hydrovar, Jason Lewis emphasises the elimination of pipes bursts: “In addition to the obvious inconvenience of having to go in and replace an underground pipe, such bursts also had the potential to cause major production losses we could loose a whole bay of fruit.“
John Fuller adds that: “Before Hydrovar was installed pipe burst averaged about one a month.“ Jason Lewis comments that, “to be honest, the energy-saving advantages of Hydrovar don't really matter much to us because we have an on-site combined heat and power plant, which provides all our power requirements, plus we deliver any surpluses to the national grid.“
Increased yield and quality
Jason Lewis summarises the benefits of the entire pumping equipment upgrade as follows: “We've enjoyed advantages from improved pumping in three main areas; firstly, capacity this certainly reduced crop yields previously, from adry spots' and other problems, and the fact that the first crop after the pump upgrade is 17percent up on previous performance is certainly in part due to the new equipment.
Secondly, the finer control of moisture delivery which Hydrovar provides has improved the quality of the fruit. And, thirdly, we now feel a lot more confident about our pumping system both in the sense that we now have the capability to water what we want, when we want and in the greater levels of reliability and control which the new system gives us.“
For more information, visit www.lowara.com
