Custom Irrigation System for a Glasshouse
The Young Plants Unit at Palmstead Nurseries Ltd posed a particularly interesting challenge when it came to the application of irrigation requirements for the whole unit. Our aim was to provide a system that was somewhat unique and used the latest technology that was available in the market place. A key feature contributing to the successful installation of the system, was the fact that the irrigation planning was conducted whilst the glasshouse was being built, allowing the opportunity of pipes to be laid during the foundation stages of development.
Working closely with the Palmstead Production Team, and contacts within the Netafim worldwide chain, a trip was made to Denmark in the early stages of planning to view modern developments of glasshouses in production. Trials were conducted on site to allow the team the opportunity to test a few of the proposed methods of application as seen in Denmark and proposals made by Netafim, prior to the final systems being proposed.
The glasshouse itself is divided into three distinct areas of production. Firstly, the Propagation area which is sub-divided into four zones. This area utilises the Netafim Coolnet range of mister. Two types of mister were used in the overall application: the Coolnet with an average droplet size of 85 micron, and the Coolnet Pro with an average droplet size of 65 micron.
The Propagation zones have been developed so that Zone 1 & 2 have under floor heating, whilst Zone 3 & 4 do not. Each zone has frost protection by means of heated pipes, as well as two layers of thermal screening. The unique Palmstead control system which monitors the house, has the ability to control the environment by means of a VPD sensor (a correlation between temperature and humidity), venting and control of the thermal screens. The Coolnet is applied in Zone 1 & 3, whilst the Coolnet Pro is applied in Zone 2 & 4. Each 'burst' length of mist is set at a 6 second duration triggered by environmental factors sensed by the control system.
The Propagation system is maintained as a pressurised system by the inclusion of a 4 Bar ADV (Anti Drain Valve) on each mister, which closes at a pressure of 1.8 Bar, holding water in the lateral lines within the Propagation zones.
As the Propagation zones are systems that require a virtually instantaneous start up when triggered to mist, the valve of choice is the Netafim Aquanet Plus hydraulic valve. These valves offer the benefit of having a low energy range, allowing the unit to respond quicker to triggers in the system. The overall system pressure is maintained at 7.5 Bar behind said valves, which allows for a quicker response in filling and pressurising lines on start up, as well as providing extra 'energy' in aiding the valves to open and close quicker on the systems.
Bringing all these features together offers the opportunity to propagate in four separate environments, with each environment being unique in its own application desirable to different plant types.
The remaining two areas (Zone 5 and 6) were developed in the sense that Zone 5 stores holding plugs, and Zone 6 stores the 8cm production, grass and division. The aim of the application was to install a sprinkler that distributed within the bay only, thus not affecting any apposing bays. The sprinkler of choice in these areas was the Netafim Spinnet SD range. The resulting set-up saw the Spinnet applied with one line of sprinklers in both the 5m and 8m wide bay areas, with extended droppers being supplied to get sprinklers to the required height above the cropping level. Each area was tested against the HDC formula of irrigation, to ensure uniformity across said systems.
Both the Coolnet and Spinnet range offer features and benefits such as being manufactured from Anti Acid raw materials, making for ease of cleaning. They are both bridgeless in design, and have interchangeable components. Both can be applied using an ADV (Anti-Drain Valves) to ensure non-leakage in the system once the system has depressurised.
All key features in the design and installation process, from correct application to pressure requirements, as well as height of mister/sprinkler placement above crops were adhered to, contributing to a successful and well managed system.