Pipe Loops

Intro

• Pilot-scale demo of CCT with flow condition • Harvested materials • Scale analysis • Long-term monitoring • Complex to implement • Large footprint • Expensive and challenging to operate

Click on buttons to learn more about each pipe loop.

• Batches of water with flow conditions • Harvested materials • Scale analysis • Sample collection challenges • Water quality changes in recirculation reservoir

DESIGN

RESOURCES

ASSESSMENT

MONITORING

HOME

CONSTRUCTION

HOME

ASSESSMENT

DESIGN

CONSTRUCTION

MONITORING

RESOURCES

The control condition provides a baseline for comparison to current water quality and treatment conditions. The control loop can also be maintained for long-term monitoring of corrosion control. EndFragment Metals release samples should be collected after a constant pre-determined stagnation period of 6 hours or more. Samples should be collected at full flow rate to evaluate particulate lead release. Sample volumes should be determined to capture water inside the pipe segment.

Test Condition

RESULTS Pipe loop results will be interpreted through comparison of metals release results between the control condition and test conditions.

CONTROL

Page 1

Pipe Loop Testing Overview

In addition to the control condition, the pipe loop system will include additional test conditions for alternate corrosion control treatment or water quality conditions. The size of the pipe loop system will vary depending on the number of test conditions to be evaluated. EndFragment A desktop study should be performed to identify specific test conditions that will be evaluated in the pipe loop.

TEST CONDITION

Pipe Loop Testing involves devices containing multiple loops, for simplicity a only a single loop is shown.

Flow Distribution Module

An automated valve is used to control daily flow/stagnation cycles. This valve opens to allow flow through the loops for a pre-determined duration. Although solenoid valves have conventionally been used, motor operated ball valves have been shown to offer greater reliability and reduced erratic lead release.

Flow Meter

CHART

For each corrosion control treatment test condition, pilot-scale chemical feed systems may be needed to achieve target pH, alkalinity/DIC, or corrosion inhibitor conditions.

Static Mixer

FLOW DISTRIBUTION MODULE

PIPES

Flow Cycle Module

CYCLES

Isolation Valve

Pipe Section Module

pH Probe

Check Valve

pH Adjustment

The pipe section module consists of pipe sections that will be exposed to different treatment conditions in the loop. Materials should be representative of plumbing materials present in the system, often including copper pipe, leaded solder, leaded brass, and lead service lines. A conditioning period should be included to acclimate new and harvested to water quality in the loop.

FLOWS

The water source for control condition should match water quality entering the distribution system, including pH adjustment and corrosion inhibitor treatment. A different source of water may be needed for test conditions to evaluate alternate treatment techniques. EndFragment

Flow Indicator

FEEDS

FLOW CYCLE MODULE

Corrosion Inhibibitor

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Water Supply Module

Pressure Relief Valve

PIPE SECTION MODULE

Chemical Feed Module

Pipe Loop Testing Modules

Back Flow Preventer

Leaded Brass (in flow tube)

The flow cycle module provides daily flow/stagnation cycles, simulating conditions in building plumbing systems, and allows collection of metals release samples after stagnation.

Water Source

Sample Tap

Harvested Lead Service Line

Motor Operated Valve

The flow distribution module splits flow between pipe sections and ensures consistent flow rates.

Copper Pipe With Leaded Solder

Sample Tap

To Drain

Metals release from the pipe sections is monitored throughout testing.

The pipe section module would typically include three replicates for each pipe material.

Harvested Lead Service Line

For systems with chemical feed, a static mixer is needed to ensure chemical dispersion and consistent water quality before entering the pipe sections.

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Brass fixtures could contain significant amounts of lead until 2014 and are a potential source of lead in many building plumbing systems. Leaded brass materials can be exposed to flow in the loop.

For each corrosion control treatment test condition, one or more pilot-scale chemical feed systems will be needed to achieve alternate pH, alkalinity/DIC, or corrosion inhibitor conditions.

A pH probe can be incorporated to ensure that chemical feed systems consistently meet target water quality conditions.

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Service lines and water meters may be copper, galvanized iron, or lead. Brass water meters may contain lead.

The water source for control condition should match water quality entering the distribution system, with all pH adjustment and corrosion inhibitor.

An upstream sample tap is needed to facilitate baseline water quality monitoring before water enters the pipe sections.

Pipe Loop Testing Components

Leaded Brass in Flow Tube

The water source for control condition should match water quality entering the distribution system, with all pH adjustment and corrosion inhibitor The water source for test conditions should not include a corrosion inhibitor. For systems that already add a corrosion inhibitor and want to test alternate types, a water source upstream of corrosion inhibitor addition would be needed. For water systems evaluating a source water change or major treatment process change, a pilot scale treatment system or partial-plant demonstration test may be needed to provide test water for the loop.

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Copper pipe with leaded solder is a common source of lead in building plumbing systems constructed prior to about 1986. New materials are often used for testing lead release from solder. Solder must be carefully applied in consistent amounts to pipe joints to ensure reproducibility. A minimum of three replicates should be included to variability in metals release. For systems with copper Action Level exceedances, the pipe loop should still include common sources of lead to ensure that treatment techniques optimize both copper and lead control.

A drain with adequate capacity for simultaneous flushing of pipe loops will be needed at the site.

Pipe loops typically include a timer or control panel to control the daily flow/stagnation cycles and chemical feed systems (if needed). Control panels can be upgraded with HMI and data logging capabilities to enhance system automation.

Copper Pipe With Leaded Solder

For systems with lead service lines, harvested lead service line segments should be incorporated, if possible, to evaluate impacts on existing scales. Additional pipe segments can be incorporated into the loop to facilitate scale analysis at key intervals. A minimum of three replicates should be used due to unique aspects of scale on each pipe segment.

A flow meter can be used to ensure accurate pilot-scale chemical feed in test conditions.

Prior to 2014, “lead-free” fixtures and valves could contain as much as 8% lead by weight. In 2014 the standard was lowered to 0.25% lead by weight.