How to install YOKOGAWA DO30G dissolved oxygen sensor?

Unable to zero/span 1. Replace membrane module+electrolyte and retry; 2. If the corrosion of the lead electrode is still ineffective, replace the sensor (lead electrode has a lifespan of 3-4 years)

Steps for replacing electrolyte and membrane components

Safety reminder: The electrolyte is KOH alkaline solution. If it comes into contact with the skin/eyes, rinse immediately with water and do not leave any residue in the syringe.

Steps:

Remove the sensor and clean the wet area;

Release the lock nut and remove the membrane component and old O-ring;

Empty the old electrolyte (tilt sensor, use a syringe to blow air from the injection port to assist in emptying);

Polishing silver electrode: Dip a damp gauze into aluminum oxide powder and gently wipe it (to avoid excessive polishing and prevent damage to the epoxy material), then clean the remaining powder;

Install a new O-ring, inject 8ml of new electrolyte (Yokogawa specific, model K9171DN), and reserve 1ml of air;

Install a new membrane component: Drop 1 drop of electrolyte on the surface of the silver electrode to prevent bubbles, lightly press the membrane component and tighten the locking nut (do not rotate the membrane component);

Rest: After replacement, it is necessary to rest for more than half a day before adjusting the zero/span (negative values may be displayed in the initial 10 minutes, which is a normal phenomenon).

Core spare parts list

DOX8A Maintenance Kit (Style B): Designed specifically for DO30G, it includes the following items:

Item Name Specification/Quantity Usage

Replace 50mL of electrolyte (model K9171DN) with 8ml each time

Replace damaged/contaminated membranes with 3 sets of membrane components and O-rings (model K9171HM)

500g of zero calibration reagent (sodium sulfite) (model L9920BR) is used to prepare a zero calibration solution (50g is required for 1L)

Inject 5ml (with needle, model L9827NH/L9827NG) of electrolyte into the syringe

200mL beaker (model L9825AF) for draining electrolyte/calibration purposes

30g of silver electrode polishing powder (model K9088PE) is used to polish silver electrodes, with approximately 0.5g used each time

Spare parts: membrane module lock nut (model K9171CH), spare sensor (to avoid measurement interruption caused by sudden failure).

Key issue

Question 1: How long does it take to replace the permeation membrane and electrolyte of DO30G sensor? What safety and operational details should be paid attention to when replacing?

answer:

Replacement cycle: It is recommended to replace the electrolyte every 6-8 months or immediately when the sensor cannot be adjusted for span; The permeable membrane and electrolyte should be replaced synchronously. If the membrane is damaged, wrinkled, or severely contaminated, it needs to be replaced in advance.

Safety details: The electrolyte is KOH alkaline solution. If it comes into contact with the skin, rinse immediately with clean water. If it enters the eyes, rinse and seek medical attention. Do not leave any residue in the syringe;

Operation details: When injecting electrolyte, add 8ml (Yokogawa specific model K9171DN) and reserve 1ml of air to prevent abnormal pressure; Before installing the membrane module, one drop of electrolyte should be dropped on the surface of the silver electrode to avoid the formation of bubbles between the membrane and the electrode; Do not rotate the membrane component when tightening the nut to prevent membrane wrinkling.

Question 2: There are three commonly used mounting brackets for DO30G sensors (PH8HG, PB350G, DOX8HS). How to choose according to the actual scenario? What are the core advantages and installation requirements of each bracket?

answer:

Selection of bracket type scene based on core advantages and installation requirements

PH8HG catheter measurement solution has no bubbles or pollutants (such as clear water tank), PVC material is corrosion-resistant, simple structure, low cost, and needs to be fixed on a pipeline with an outer diameter of 60.5mm. The sensor is suspended in a 2m long catheter

The PB350G floating ball bracket measures the solution level with large fluctuations and a small amount of flocculent substances (such as sedimentation tanks). The floating ball changes with the liquid level, and the sensor is always immersed in the solution; The wet part is smooth and not easy to hang flocs. The bracket is fixed on the 50A pipeline (outer diameter 60.5mm) or horizontal plane, and the float does not deviate from the measurement point

The DOX8HS immersion bracket measurement solution is prone to contamination (such as industrial wastewater) and needs to be regularly cleaned and installed at a 45 ° angle to prevent bubble adhesion; Support automatic cleaning with water/air spray to reduce the need for manual maintenance by connecting to a clean water/air source. The sensor is tilted and fixed to ensure that the cleaning spray port is aligned with the membrane surface

Question 3: When the DO30G sensor displays abnormal measurement values (such as continuous low or large fluctuations), how to gradually investigate the cause of the fault and solve it?

Answer: Troubleshooting should be carried out according to the following steps, with priority given to handling simple faults: