Schneider Square D 9036/9037/9038 Electromechanical Liquid Level Controller

Connecting rod length selection: Select the appropriate length of stainless steel connecting rod (1.75 inches to 12.25 inches) from 9049ER1 to ER12 according to the depth of the tank body. Note that the same switch may require multiple adjustment sizes such as "H", "A", "B", "C", "D", "F", "G", etc. Please refer to the original size chart for details. It is recommended to first measure the range of liquid level changes in the tank, and then compare the table to select the connecting rod number that meets the minimum/maximum travel requirements.

Pressure test: After installation, conduct a pressure test on the tank body (not exceeding 50 psi) to check for any leaks at the seal.

3.3 Special debugging of 9038 mechanical alternators

The core logic of the alternation device:

The liquid level rises to the "first pump start" point → pump 1 runs.

The liquid level continues to rise to the "second pump start" point (high level) → Pump 2 also runs.

The liquid level drops to the "first pump stop" point → pump 1 stops (pump 2 continues to run).

The liquid level drops to a low level (the second pump stops) → Pump 2 stops.

When the liquid level rises next time, it will automatically switch to start pump 2 first and pump 1 as a backup, so as to alternate back and forth.

Debugging steps:

Choose float kit: Open can (9038A) uses 9049A6C center hole float (recommended with compensating spring). The closed tank (9038C/D) uses 9049EF1/EF2 floating balls and corresponding connecting rods.

Set stop rings: The position of the four stop rings determines the start/stop liquid level of the two pumps. According to the size of the tank body, refer to the dimensions of "A", "B", "C", "D", "F", and "G" in the original factory tables 20-23 to locate the stop ring. For example, for 9038DG7 (short hinge pillar), when using 9049ER1 connecting rod, A (minimum stop ring to hinge center distance) is 0.75 inches, and the maximum is 0.63 inches (note that the maximum is less than the minimum? The actual adjustment range given in the table needs to be carefully read). Strongly recommend: Assemble the float and connecting rod outside the tank first, manually simulate the liquid level changes, and use a multimeter to monitor whether the contact alternation sequence is correct.

Optional features:

Manual transfer switch (Form N3) - allows the operator to forcibly specify which pump to start first.

Two level non alternating mode (Form N4) - Cancel the alternating function, only for high and low level control.

High water level alarm (Form N5 single blade/N25 double blade) - triggered when the liquid level exceeds the starting point of the second pump and still does not stop.

Common troubleshooting (required reading for on-site engineers)

Fault 1: The float does not move with the rise of the liquid level

Possible reasons:

Perforation of the floating ball into the liquid (check the weight of the floating ball, the normal 7-inch 304 floating ball is about 0.5 pounds, and if it becomes significantly heavier, water will enter).

The connecting rod is stuck by an obstacle inside the tank.

Insufficient buoyancy (medium density too low or connecting rod too long exceeding buoyancy limit).

Compensation spring failure or not installed.

Solution:

Replace the float (original replacement: 9049AF1/AF2 center hole float, 9049AF3/AF4 top attack float).

Reposition the float path and install guide pipes if necessary.

Recalculate buoyancy, and if there is negative buoyancy, install compensating springs (such as 9049A19, 9049A15, etc.).

Check if the compensating spring is corroded or broken, and replace it with a spring of the same model.

Fault 2: The switch contacts do not switch or do not reset after switching

Possible reasons:

Micro switch wear (especially in high-frequency operation scenarios).

The position of the stop ring is incorrect, resulting in insufficient float travel to trigger the switch.

The switch lever is deformed or the pivot point is rusted.

Solution:

Replace the switch mechanism (spare part number: 9998PC213 for 9036GR/GW series, 9998PC286 for 9036DR/DW series, etc.).

Adjust the position of the stop ring again. The minimum differential travel specified by the original factory is 0.375 inches (standard) or 0.5 inches (reverse action). Measure the actual displacement of the lever using a feeler gauge.

Clean and lubricate the pivot point using lithium based grease.

Fault 3: Leakage at the seal of the 9037 sealed tank

Possible reasons:

The Quad ring seal ring is aging (nitrile rubber has a lifespan of about 2 years at high temperatures).

The flange bolts are not tightened evenly.

The tank pressure exceeds 50 psi.

Solution:

Replace the sealing ring. The original factory provides Viton material kits (Z19, Z20, Z21) with a temperature resistance of up to 250 ° F.

Tighten the bolts in a cross sequence, with torque reference to the flange standard.

If the tank pressure is indeed higher than 50 psi, other types of liquid level transmitters should be used instead.

Fault 4: The 9038 alternator does not alternate and always starts the same pump first