Valve exercising creates new opportunity for contractors.
In many cases these water valves have been neglected, but a Homeland Security directive as a result of the 9/11 attacks has raised the importance of these often unnoticed valves. They need to be in top working order should a municipality need to shut off water valves quickly to contain contaminated water flow and prevent it from spreading throughout a community.
Because of this concern, cities must have the ability to reach the valves quickly to shut the water flow off. However, some of these valves may not have been paid much attention for years and thus the water valve boxes may be filled with compacted sediment, making them hard to reach, and taking several hours to clean by hand.
First, some background about water valve boxes. A water valve box is an eight-inch diameter tube that stretches from the ground surface down to an underground valve, which can be eight-feet below the surface, depending on the freeze line. When it rains, water and sediment flow into the box and over time the sediment becomes compacted. In the event of a water main break or contaminated water, a sediment filled valve box slows down the process of reaching and closing the valve.
Valve exercising is a maintenance activity. So a valve exercising equipment that turns fast is ideal, but it should not exert too much torque. Excessive torque can damage a valve leading to an unexpected repair. If the valve will not open or close, then it likely needs to be replaced and putting too much torque on the valve could lead to additional repair issues that need to be resolved immediately versus scheduling the repair.
For example, a six-inch valve may require 19 rotations to open and 19 to close. If fewer rotations are taken to open and close the valve, then the city may not be receiving all of their water flow and valves need to be exercised further to break up sediment inside until they reach their full rotation.
Tools of the trade
Hand-held valve exercise equipment has been around for years. These units arc operated by one or two people, depending on the size of the unit, and powered by an auxiliary hydraulic pump or gas engine. Depending on the size of the valve, it can take from 10 minutes to an hour to fully open and close. While these units are easy to transport, they do not provide the means necessary to clean out the valve box. In many cases another crew needs to accomplish that task. This is where vacuum excavators come in.
Until now, vacuum excavators are self-contained units that use pressurized air or water to displace spoil with a pump to remove the displaced spoil. The displaced dry or wet spoil is stored in a holding tank on the vacuum. They can be mounted to a trailer or the back of a truck and range in size from 100 to 1,200 gallons of capacity and have traditionally been used for potholing or identifying existing utilities during underground construction projects.
Manufacturers, such as McLaughlin, saw a need and developed a way to efficiently clean the valve boxes and not only exercise the valve, but log data on each valve as well for future reference and maintenance.
"We combined the valve exerciser with the vacuum excavator allowing a municipality to take one piece of equipment out into the field, saving time and labor, while providing a smaller footprint," says Dave Gasmovic, president of McLaughlin, based in Greenville, SC.
The system uses high-pressure water delivered through a spray wand to dislodge the sediment from the valve box. Then, the vacuum excavator removes the sediment from the water valve box. Once the sediment is removed from the valve box, a valve exerciser can be inserted to open and close the water valve.
Municipalities are faced with a daunting challenge--to identify, clean and ensure the operating order of water valves throughout a community. Depending on the size of the community, the number could be in the hundreds for a small town to thousands for a large metropolitan city.
But this directive is also creating an opportunity for independent contractors to conduct the work on behalf of the municipalities.
"Most municipalities are completing the work themselves," says Gasmovic. "However, there is a real opportunity for contractors to fill this role as smaller municipalities may prefer to contract the work versus purchasing another machine to complete the valve box clean-out and valve exercising. It's a little too large of an investment for some communities."
Opening and closing isn't the only role of a valve exerciser. These units have the ability to collect data and create a detailed log of all valve and hydrant exercising activities. The system tracks critical information such as applied peak torque, revolution number at peak torque, and number of revolutions required to open or close a hydrant or valve. Plus some units can be equipped with a hand-held global positioning system (GPS) to record the exact location of each valve box. Should a valve need to be repaired, the exercising crew can note the exact coordinates and pass the information along to the repair crew, saving time.
"The torque required to open and close a valve is important information," says Gasmovic. "If you go back and the following year and more torque is needed to open and close a valve, then it's a good indicator that the valve may be damaged."
When selecting a valve exercising system, the best advice Gasmovic can offer is to look at both items--the valve exerciser and the vacuum excavator--as two separate items.
"You want to get the best in both," says Gasmovic. "There are very good valve exercisers paired with a low-cost or subpar vacuum excavator designed just to complete the cleanout of the valve box and exercise the valve. That's fine for valve exercising, but it limits the potential other uses for the vacuum."
Once a municipality starts their valve exercising program and completes the first round of clean-outs, they discover that while the valves need to be exercised annually, the valve boxes don't need to be cleaned every year. The municipality can split the valve exerciser from the vacuum and mount it to a truck with a small hydraulic power pack for the subsequent valve exercising activities. This also provides an opportunity for the vacuum to be used for other projects within the municipality.
The vacuum has the capability to be used for potholing for utilities, cleaning catch basins and even digging post holes. However, the vacuum you select needs to have the power to complete these other tasks.
Gasmovic also suggests that you select a vacuum system that is compact in size and can easily navigate the street system in your community. The most commonly used vacuum excavator for valve exercising is a 250-gallon machine, while some prefer a 500-gallon unit.
There are two common types of valve exercisers on the market. A scissor-type valve exerciser arm opens and expands from the vacuum in the scissor-type fashion. The advantage is that this type of system allows you to maneuver the arm over a small fence or other obstacle in order to reach the valve box. The other option is a sling-out-arm valve exerciser. This type of system does not offer as much vertical (up and down) mobility, but provides more stability. Therefore, on larger valves not as much torque will be absorbed by the sling-out arm.
Also select a valve exerciser that is easy to dismount from the vacuum excavator and has the ability to electronically collect and record data from each valve. The valve exerciser should also provide a range of motion. Some units offer 15 feet of reach and 270 degrees of rotation, allowing multiple valves to be exercised from a stationary spot, helping to save time.
Gasmovic also encourages contractors to pay special attention to the filtration system and select a system that will filter the spoil and avoid clogging--such as a three-stage cyclone filtration system that allows for both wet and dry vacuum excavation. Many manufacturers use bag house filtration systems. In simple terms, a bag house filtering system is just like the bag on a vacuum cleaner. Should the bag get wet prior to dust and debris being introduced, a layer of mud will form on the outside of the bag, limiting performance--and in some cases--requiring you to stop work to wash the bag.
Valve exercising may be a new market that can help provide additional uses for your vacuum excavator and a new source of revenue. Just take the time to research the market and explore how municipalities in your area are addressing this directive. A little exercise never hurt anyone, and as cities across the country can attest, this exercise movement will be around for some time.
FOR MORE INFORMATION:
(800) 435-9340, www.mightymole.com
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||Vacuum Excavator|
|Date:||Apr 1, 2011|
|Previous Article:||PLCA's 63rd annual convention attracts large crowd.|
|Next Article:||Defining, understanding lateral rehab options.|