PAC Dosing System Installation: Foundation to Water Test, Step by Step

PAC dosing system installation follows five steps: prepare the foundation, lift and level the skid, connect the piping, wire the electrics, then commission with clean water before any chemical goes in. Keep that order. Most packaged PAC units arrive with the tank, mixer, metering pumps and valves already on one base, so the site work looks small, yet an uneven base, pipes forced into alignment or a motor running backwards often only show up after dosing starts. This guide is for installation contractors and the owner's site engineer, and it covers construction only, not daily operation.

Step 1: Foundation and floor for PAC dosing system installation

Set the unit on a concrete plinth or a level, hard floor, with the plinth slightly higher than the surrounding floor so wash water drains away. A chemical-resistant floor coating is worth it, and a drain channel around the tank lets spills and wash water run off instead of pooling under the skid.

Build the plinth to the supplier's base drawing and check that anchor bolt holes line up with the base frame. If the unit sits on a suspended slab, have the structural engineer confirm the load first. A full tank weighs far more than an empty one, and that is easy to forget during PAC dosing system installation. For room layout, see our notes on PAC dosing room design and where to install a dosing system.

Step 2: Lifting, setting and leveling

In PAC dosing system installation, lift from the base frame or the marked lifting points. Never hook the mixer bracket or the tank rim; a PE tank loaded unevenly can deform or crack. Once in place, level the skid with a spirit level, pack shims solidly under the base, then tighten the anchor bolts.

Leave service space around the unit. There should be room to kneel in front of each metering pump and remove the pump head, enough height above the mixer to pull the shaft out, and clearance for the control panel door to open fully. Skip this during PAC dosing system installation and every future repair means dismantling something else first.

Step 3: Piping connections

PAC dosing system installation involves four kinds of lines, each with its own rules:

1. Water inlet: from mains or reuse water, with a manual valve and, where needed, a strainer to keep debris out of the tank.
2. Dosing line: from the pump discharge to the injection point, in a chemical-resistant material, as short as possible, with few bends and proper supports.
3. Overflow and drain: run to the floor drain channel, not into a closed pipe, so overflow is visible.
4. Pump discharge accessories: back pressure valve, safety relief valve, pulsation dampener and pressure gauge, placed as shown on the supplier's drawing.

When the pressure difference between pump discharge and suction is below 1 bar, fit a back pressure valve, or flow will be inaccurate and siphoning may occur. Standard positions are shown in our metering pump installation diagram.

Pipes should meet the equipment flanges naturally. Never pull them into line with the bolts, because constant stress on pump heads and valves leads to leaks. Let PVC solvent joints cure fully before pressure testing. At the injection end, push the line into the flow and fit an injection valve so chemical cannot drain back or drip onto the tank wall when the pump stops. On long runs, add flushing connections at intervals; clearing PAC crystals later becomes much easier.

Step 4: Electrical hookup

The electrical part of PAC dosing system installation starts with a simple check: compare the motor nameplate voltage with the site supply before power-up. Earth the skid and the control panel properly. Run cables in conduit and mount the panel away from chemical mist and wash-down spray.

After wiring the level sensor, confirm that low level stops both pumps and mixer so nothing runs dry. Bump each motor once and check rotation; if it is reversed, swap any two phases. If remote start/stop or a 4–20mA signal goes to the control room, agree terminal numbers with the DCS team now. A joint point-to-point check with the electrician and process engineer is much faster than tracing wires during commissioning.

Step 5: Commissioning PAC dosing system installation with clean water

Use clean water only. Fill the tank to normal level and check the tank, valves and joints for leaks. Run the mixer briefly, then continuously for a while, listening for noise and watching for shaft wobble.

Before starting a metering pump, make sure its discharge valve is open. Start at a short stroke and purge air from the pump head and lines. Measure real flow with the calibration column and compare it with the setpoint; if the gap is large, check the back pressure valve and suction line. Hold the full piping under pressure and watch for leaks before handover; a leak found now costs minutes, while one found after PAC dosing system installation is signed off costs a site visit.

After the water test, mix the first batch at design strength and dose at low flow, checking that chemical reaches the injection point smoothly. Only then is PAC dosing system installation truly finished. Use our list of PAC dosing system components to tick off every item.

Conclusion

Successful PAC dosing system installation is about order and detail: a level, protected foundation; correct lifting points and solid shimming; piping that aligns without force and accessories in the right place; voltage, earthing and rotation checked; and a clean-water test before chemicals. Follow these steps and most post-startup rework can be avoided. For complete units, see our chemical dosing skids, or contact our engineers with your drawings and site photos.

FAQ

How long does PAC dosing system installation take?

It depends on size and site conditions. With the foundation ready, setting, piping and wiring a packaged skid typically takes a few days, plus commissioning time.

Can the tank sit directly on soil?

It is not recommended. Uneven ground stresses the tank and standing water corrodes the base, so at least provide a hard, level floor.

Can galvanized steel be used for the dosing line?

Usually not. PAC is corrosive, so dosing lines are normally UPVC, PE or another resistant material chosen for chemical and pressure.

The pump delivers nothing during the water test. Why?

Most often there is air in the pump head or a stuck suction valve. Open the bleed valve, then check the suction line for air leaks.

What documents should be handed over after installation?

Keep the wiring diagram, piping layout, calibration record and water test record. They make later maintenance and troubleshooting much easier.