LMI Roytronic Series A Pump Tubing Connections

Tubing Connections

Precautions Pump OperationUse only LMI tubing.

DO NOT USE CLEAR VINYL TUBING ON THE DISCHARGE SIDE OF THE PUMP. The pressure created by the pump can rupture vinyl tubing, which is only for connection to the return line of the FastPrime™ fitting.

Precautions Pump OperationBefore installation, all tubing must be cut with a clean square end.

Valve and head connections from the factory are capped or plugged to retain pre-prime water. Remove and discard these caps or plugs before connecting tubing.


To assemble tubing into the fittings:

  1. Put coupling nut over tubing.
  2. Press on Ferrule – Female about one inch (25 mm).
  3. For 1⁄4″ or 6mm OD tubing cut tubing so that only 1⁄4″ to 3⁄8″ (5-10 mm) protrudes from the Ferrule. For all other tubing push the tube to the bottom of the groove in the Ferrule – Male.
  4. Firmly hand tighten the coupling nut onto the fitting. Tightening with pliers may cause the ferrules to break.

Manual LMI Pump

Four-Function Valves (4-FV)

Your pump may be equipped with a 4-FV, or standard discharge valve. If your pump is not equipped with a four-function valve and you feel it is needed in your application, it can be purchased as an  accessory. Contact your local LMI stocking distributor. The features of a 4-FV are listed below.

  1. Pressure Relief: If the discharge line is over pressurized, the valve opens sending solution back to the supply tank.
  2. Line Depressurization: Opening the relief knob provides line drain back to the supply tank.
  3. Anti-Syphon: Prevents syphoning when pumping solution downhill or into a vacuum.
  4. Back Pressure: Supplies approximately 25 psi back pressure to prevent overpumping when little or no system back pressure is present.

LMI Chemical Pumps US

Typical Installations Requiring the Anti-Syphon
Feature of a Four-Function Valve

Four-Function Valve Installation

Four-Function Valve Tubing Connection


Valve Body LMI
Click to Enlarge Image

Four-Function Valve Tubing Connection

To install a 4-FV, the 4-FV Fitting and Coupling Nut should be assembled with the appropriate cartridges into the discharge port of the pump. Use a 13/16” or 20 mm socket to tighten fitting. Tightening to 50 inch-pounds is recommended. Do not over tighten.

To assemble the Four-Function Valve Body, assemble the coupling nut and the threads at the bottom of the body. Firmly hand tighten the body in the desired orientation. Next, insert the ¼” tubing through the Bleed Nut. Ensure that about ¼” (6 mm) of tubing is protruding through the tip of the Bleed Nut. Firmly hand tighten the Bleed Nut in the hole on the side of the 4-FV. This tubing should be routed back to the supply tank. To ensure proper function of the priming function, the end of this tubing should not be submerged in the solution..

Four-Function Valve Tubing Connection

Precautions Pump OperationThis return line tubing must be secured to ensure pumped solution will safely return to supply tank.

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