The results available with high pressures are usually available at low pressures as well: it simply takes longer. Low pressure injection is popular largely because of the low initial equipment cost and ease of installation. The procedure is straightforward, requiring little equipment and know-how.

The LPI system is ideal for small projects and unique conditions that prohibit the use of significant pressure. For example, low pressure techniques are often used for delicate architectural surfaces because they allow the use of low strength capping adhesives such as sealants that can be removed without marring the surface of the concrete.

The dispenser consists of a steel frame with a collar to support the disposable bowl, a lid, a clamping device to secure the lid, and brackets to mount a regulator and pressure gauge. The pressure regulator is specially manufactured so that the dispense pressure cannot exceed 15 psi. (1 bar).

The unit can be pressurized from any clean air source, such as an inexpensive 5 gallon tank.

Resin is pre-mixed in a disposable plastic bowl which is then pressurized to flood a circuit of plastic tubing connected to a series of porting adapters. All of the ports are injected simultaneously. Pressure is maintained until the resin has gelled within the tubing.

The adapters, tubing, and bowl are usually left in place until the resin has hardened. They can then be disposed of in a fully cured and environmentally friendly condition.

Since the LPI uses very low pressure, penetration requires more time than with higher pressures. For this reason, super thin resins with a long working life work great.

A tool (M-260) is used to set the pedestals. It holds the pedestal as a capping adhesive is applied and guides it to its precise location.

The tip of the tool also protects the opening into the void from oozing adhesive that may otherwise clog it.

The capping adhesive is applied over the crack to retain the injected resin. At the same time, additional adhesive is applied over the base of the pedestal. The adhesive is the same for both applications.

After the adhesive has hardened, the tees are snapped onto the pedestals.

A soft plastic tubing (T-101) is then cut in segments to plumb the ports in series — like Christmas tree lights. Cracks 30' in length can often be injected in a single setup. Tees (P-830) and crosses (P-831) are used to route the tubing to more than one crack.

The tubing is drawn through a hole in the lid over the resin bowl of the dispenser, and submerged in the resin. The resin is pressurized by adjusting the knob on the regulator.

A unique feature of the dual component adapter is that the flow to a particular port can be closed by pressing the tee to a second notch on the pedestal. This closes off the flow to the local port, yet allows flow to continue to remote ports. This is useful in the event of a leak in the seal because nearby ports only can be closed off rather than scrubbing the process entirely.