Power outage can be a common occurrence during a severe rain storm. The sump system in a home typically relies on a heavy duty AC primary pump to discharge water entering the home through its drainage system. To compensate for the possibility of a power outage, the sump pit may include a battery-operated DC or AC driven pump in addition to the primary pump. How do these AC/DC pumps differ in function and performance?
A DC based back up system typically consists of a DC pump, a 12 volt deep cycle battery (2 batteries if a 24 volt system), and a charger. Most DC pumps used as part of a back-up system were initially designed to be bilge pumps for boats and are not heavy duty, but some work well. A characteristic of a DC system versus an AC system is that the rate that it discharges is related to the degree that the battery power source is charged. A fully charged 12 volt battery will power the DC pump to its maximum capability. As the charge of the battery is consumed, the pumping rate of the DC pump diminishes. For example, a given pump will discharge at the rate of 30 gallons per minute with a fully charged battery, but may only be pumping at 15 gallons per minute when half of the charge is still left with the battery. At the end when the battery is about to be depleted, the pump may be discharging at less than five gallons per minute. DC systems efficiently consume DC current and can run continuously for several hours (up to 10 hours continuously and intermittently for several days).
Dewalt 12 Saw Blade
An AC based back-up system typically consists of an AC heavy duty pump, a 12 volt deep cycle battery (or two batteries if a 24 volt system), and an inverter with a battery charger). An inverter converts the DC power of the battery to its AC counterpart. Unlike a DC pump, an AC pump will run close to its maximum potential capability until the battery charge is depleted. For example, if the AC pump can pump at a rate of 50 gallons per minute, it will continue at close to this rate (with minimal loss over time) until the battery power source is depleted. It is important to select an AC pump with efficient amperage rating (3-7 amp hours), otherwise the system will not run long enough before the battery source is depleted and the system shuts down. An efficient AC pump can discharge as much as the best DC system because it is discharging at a greater rate than most DC systems even though it shuts down faster than a good DC pump system. The key advantage of going with an AC system is that it is easier to match it up with its primary pump counterpart. Since the AC system requires an inverter, it is typically more expensive than DC systems which do not require an expensive inverter for its operation.
The best way to compare different available systems is to compare the total amount of gallons discharged with a given battery (beginning with a fully charged battery recommended by the manufacturer) and that the data, ideally determined by an independent testing agency, represents the time and performance until the system shuts down). The values should have been generated at an 8-10 ft. head. The head is the distance that the pump discharges vertically (in a basement, it is usually 8-10 ft).
For the most part, A DC system will discharge at a rate less than the primary pump can discharge. Whether this is good enough is something that the homeowner and/or contractor must make a judgment call on. An AC system can be matched more effectively to the performance of the primary pump. The best scenario is that the homeowner has determined how effectively his primary pump has performed during a major storm and matches that performance with that of the back-up system, whether it be an AC or a DC system.
Christmas Sales DEWALT D28715 14-Inch Quick-Change Chop Saw 201
Dec 11, 2011 14:21:46
Click for larger image and other views
Christmas Sales DEWALT D28715 14-Inch Quick-Change Chop Saw Feature
- Powerful 15.0 Amp/5.5 hp (maximum motor hp) motor provides more overload capacity
- Quick-Change blade change system lets users change wheels without a wrench
- Patented Quick-Fence tool-free, 45 degree adjustable fence allows for fast and accurate angle cuts
- Quick-Lock vise allows for fast clamping on different size materials
- Soft start extends gear and motor life, ergonomically designed handle
Christmas Sales DEWALT D28715 14-Inch Quick-Change Chop Saw Overview
Quick, accurate crosscuts are easy to execute with the DEWALT 14-Inch Chop Saw featuring Quick-Change keyless wheel changes. The exclusive Quick-Lock Vise lets you secure materials fast, while the powerful 15 amp motor makes quick work of tough cuts. This saw also features convenient wheel changes and a portable, ergonomic design that's easy on your body, so you can work smarter for longer.
|
 Featuring a heavy-duty 15 amp motor that delivers a no-load speed of 4,000 rpm. View larger. |
 Cut rounds measuring 5 inches across and rectangular materials up to 4-1/2 by 6-1/2 inches. View larger. |
Thanks to a 15 amp, 5.5-horsepower motor with overload protection and a no load speed of 4,000 rpm, this saw is powerful enough for tough applications. This DEWALT saw features a 14-inch wheel and can handle rounds that measure 5 inches across or rectangular materials as large as 4-1/2 by 6-1/2 inches. You can expect square, accurate cuts from this DEWALT saw.
This chop saw features an ergonomically designed D-shaped handle that allows you to position your hand comfortably, reducing user fatigue and increasing productivity and accuracy.
Convenient Features for Accurate Cuts
It's the details that make this DEWALT saw an impressive, versatile addition to your tool collection. The DEWALT Quick-Lock Vise allows you to clamp a wide variety of materials quickly and securely, allowing for faster transitions and increased efficiency.
When it comes time to do more than make 90-degree cuts, a 45-degree pivoting fence allows for fast, accurate angle cuts. The saw's steel base allows you to weld jigs or stops directly onto the base for a custom user experience that matches your most common applications.
In addition, the saw arm's compression spring provides smoother movement and increased durability compared to arm setups that use torsion springs. An adjustable spark guard allows you to direct sparks away from your work area, protecting both your body and work surfaces.
Quick, Tool-Free Wheel Changes and Easy Transport
When it comes time to replace the abrasive wheel, the Quick-Change blade change system allows you to change wheels without a wrench. So you never waste valuable time looking for the right wrench to complete the job.
At just 21 inches long and weighing 39 pounds, this chop saw is compact and portable. An integrated top handle makes it easy to carry the saw from your workshop to your vehicle or from your vehicle to the jobsite. For added convenience and safety, a heavy-duty lock-down pin allows the saw head to be locked in the carrying position without the use of a chain.
This 14-inch chop saw with Quick-Change comes with a DEWALT warranty package that includes a three-year limited warranty, a one-year free service contract, and a 90-day money-back guarantee.
What's in the Box
D28715 DEWALT 14-Inch Chop Saw, 14-inch abrasive wheel, fence wrench, and tool-free flange system.
 The Quick-Change blade change system allows you to change wheels without a wrench. |
SAVE NOW on Christmas Sales Offers below!
Available In Stock. |
| This Christmas DEWALT D28715 14-Inch Quick-Change Chop Saw ships for FREE with Super Saver Shipping. |
Price : Click to Check Update Prices Please. |
