PREVENTIVE AND CORRECTIVE ACTION
1. Provide 1,5 Kg/cm2 minimum pressure at the end of branch lines.
2. Use a filter of a minimum of 150 mesh.
3. Chemical blockages:
Prevention: at the end of the day apply, the necessary amount of acid needed to reduce the pH from 6 to 6,5 (if the crop allows it) leaving it until it reaches the furthest transmitters, increase the time estimated from 50 to 100%, to make sure. This ensures that the water retained in the drippers and in the pipes from one day to the next is always at the proper pH so avoiding the formation of precipitates.
Cleaning (without crops): Between one crop and the next, a concentration of nitric acid higher than 1% should be applied for 10 minutes, timed from the moment that the acid reaches the last transmitter in the furthest branch line. Then the tap should be closed to let the acid work for 6 hours, after which time the pipes must be flushed out for a few minutes with water only, at maximum pressure.
4. Biological blockages:
- Reservois:: If it is an open-air reservoir (i.e. not protected from the sun), the following amounts of copper sulphate, potassium permanganate or sodium hypo-chlorine shown in the table are added. Preventive treatment with algaecide has to be done every time the water is renewed, and at least once a week in summer and once a month in winter.
- Treatment with chlorine in primary, secondary pipes, branch lines, dripper-carriers and drippers:
- Prevention: There are several products available: liquid sodium hypo-chlorine, gas chlorine (Cl2) and solid chlorine such as calcium hypo-chlorine.
- Cleaning: This is best carried out in the absence of crops, if treatments are to be carried out with high doses of chlorine (doses of higher than 50 PPM active chlorine at the beginning).
- Continuous chlorination: Maintain a permanently a free chlorine concentration of between 1 and 2 PPM at the furthest transmitter.
- Intermittent chlorination:In this treatment, a concentration of higher than 5 PPM free chlorine should not reach the end of the furthest transmitter, if there are crops. The application dose should be between 15-50 PPM. Apply it for between 45 minutes and 1 hour.
- Shock treatments: If a great development of micro-organisms is detected, treatment with sodium hypo-chlorine is more effective. A sodium hypo-chlorine solution should be added at the necessary concentration for the water to carry 3 parts per thousand of sodium hypo-chlorine to the outlet of the drippers (100g active chlorine per litre). This takes 1 hour.
- Continuous chlorination: Ensure a permanently free chlorine concentration of between 0,5 and 1 PPM (parts per million) at the furthest transmitter. For this purpose, an estimated dose of approximately 3-5 PPM at the application point will be necessary.
- Intermittent chlorination: Maintain a free chlorine concentration of between 1 and 2 PPM at the furthest transmitter for a period of between 45 minutes and 1 hour, every 6 hours maximum. For this purpose, an estimated dose of approximately of 5-10 PPM at the application point will be necessary. It is not advisable to apply chlorine in the last irrigation hour.
A general formula to calculate the amount of injected product is:
IC= Amount of chorine to inject in L/hour.
Q= Flow of the irrigation system.
C= Concentration of the desired chorine in PPM (parts per million).
R= Richness of the product in %.
Example: For a flow of 20 m3/h, if we want a 10 PPM concentration where the chlorine to be added is 80% pure:
