Services offered by Mark Controls :
1. General Check up of the RO Plant
Advised when the plant has not been used for some time or it is not performing with complete effeciency. All the parts are checked one by one so as to diagnose the correct condition of the machine. This also helps in forecasting future trouble shootings which may arise in future and preventive measures required to keep the unit functioning with full effeciency.
Following part wise inspection is carried out :
- 1. Pre-filters
- 2. Power switch
- 3. High pressure pump
- 4. Solenoid valve (pump inlet valve)
- 5. Solenoid valve (auto flush valve)
- 6. Pressure regulator valve
- 7. Electronic control
- 8. Inlet pressure gauge
- 9. Concentrate pressure gauge (waste)
- 10. Recycle line flow meter
- 11. Permeate flow meter (product water)
- 12. Membrane housing (s)
- 13. Membrane (s) (not shown)
- 14. Starter motor box
- 15. Recycle line valve (optional)
- 16. Low pressure switch
- 17. Power cord
- 18. Level switch connector for storage tank
2. Membrane Removal & Replacement
Maintaining a constant TDS level is a good indication your RO system is working properly. It is advisable to replace membranes when TDS levels increase or flow has diminished to unacceptable limits. For this reason, it is essential to keep a periodic log to record TDS levels. The timing of membrane replacement depends on feed water quality and a number of other factors. To optimize performance and prolong membrane life membranes should be cleaned periodically.
3. Membrane cleaning
Periodic cleaning of membranes can improve system performance. In normal conditions, mineral scale, biological matter, colloidal particles and organic substances can foul membranes.
4. Inorganic Anti - fouling cleaning
An acid cleaning solution is used to remove inorganic salts such as CaCO3, CaSO4, BaSO4 and metal oxides, such as iron from reverse osmosis membranes. Sulfuric acid is never used in such cases because it may cause calcium sulfate to precipitate on the membranes.
Below mentioned cleaning solutions are used for inorganic cleaning :
- Solution of 0.2% hydrochloric acid (HCL)
- Solution of 0.5% phosphoric acid (H3PO4)
- Solution of 0.2% sulfamic acid
- Solution of 1.0% sodium hydrosulfite
5. Organic anti-fouling cleaning
Alkaline cleaning solutions are used to remove silica, bio films and organic matter from membranes. Acceptable cleaning solutions for organic cleaning include:
- Solution of 0.1% sodium hydroxide (NaOH)
- Solution of 0.1% sodium hydroxide (NaOH) and 0.1% of tetra-sodium salt of ethylene diamine tetraacetic acid (Na-EDTA)
- Solution of 0.1% sodium hydroxide (NaOH) and 0.05% sodium salt of dodecyl-sulfate (NaDDS)
- Solution of 1.0% sodium triphosphate (STP), 1.0% trisodium phosphate (TSP) and 1.0% Na-EDTA
The pH of the solutions above is maintained around 12.
Hydrogen peroxide or renalin may be use for disinfection.
Procedures are identical to the membrane cleaning directions described above, with the following exceptions:
1. Deposits on membranes and other system parts are removed with an alkaline cleaner prior to disinfection.
2. RO system is cleaned with an acid cleaner to remove iron from membranes. (Iron or other heavy metals catalyze membrane degradation when peroxide is present.) and is then flushed with water after acid cleaning.
3. A solution of 0.2%-0.25% hydrogen peroxide or renalin and RO product water is circulated for 20 minutes. The solution temperature is maintained below 77° F (25° C) to prevent damage to membranes. (A pH of 3-4 optimal results and longer membrane life.)
4. Membranes are then soaked in a disinfecting solution 2 - 12 hours. (Two hours is needed to kill 90% and 12 hours is needed to kill 99% of the bacteria present.)
7. Annual Maintenance Contract
The entire machine is first checked and then a quotation is submitted with complete Terms , Conditions and Services to be provided within the Contract period.
The Annual Maintenance Contract provides 4 nos. of Mandatory Services for the Reverse Osmosis Plant.
8. Trouble shooting
Common Trouble shooting with corrective actions are addressed in below table :
|S.no||Problem||Probable Cause||Corrective Action|
|1||RO is not making enough water||Water temperature is too low||Control temperature|
|Low water supply pressure||Check prefilter & replace|
|RO membranes are fouled||Clean/ replace membranes|
|Low RO pump pressure||Adjust reject valve|
|Increasing product pressure||Check piping and valves|
|Feed water TDS very high||Common occurrence|
|2||RO is making too much water||O - ring bypass in membrane vessel||inspect O -rings sealing|
|Chlorine damage to membrane||Replace membrane|
|Water temperature has increased||Control temperature|
|reverse flow - ruptured membrane||Replace membrane|
|3||TDS in product water too high||O - ring bypass in membrane vessel||Inspect O - rings|
|Chlorine damage to membrane||Replace membrane|
|Membrane is fouled||Clean or replace|
|Reverse flow causing rupture||Replace membrane|
|Feed water TDS has increased||Cannot be adjusted|
|4||RO pump not staying ON||Low water pressure supply to unit||Check prefilters/ supply pressure|
|Reject valve is fully open||Adjust reject valve|
|High Pressure light is ON||Adjust reject valve|
|5||RO pump running but no water||Instruments not reading correctly||Calibrate or replace|
|Blockage in water lines||Check and correct|
|Reject flush solenoid is open||Check flow thru valve|