|
|
| Main Menu |
|---|
| International Info | ||
|---|---|---|
|
| General |
|
Frequently Asked Questions:
Q: How long has Go-Power Systems been in business?
A: Since 1958, Go-Power Systems has been providing the engine testing industry with reliable, portable dynamometers and test cell equipment for a variety of industry disciplines. We manufacture and supply testing solutions for high output small engines, production and performance automotive, heavy diesel engines, and even aerospace. For 50 years, we’ve established a customer base that stretches around the globe. Our staff continues to maintain excellent relationships with these industry’s veteran engine testers and novice testers alike. Today, customers new and old have come to rely on the durability and repeatability a Go-Power Systems portable dynamometer system offers.
Q: What is Froude Hofmann, Inc. and how is it related to Go-Power Systems?
A: Go-Power Systems was incorporated with Froude Hofmann, Inc. in 2002. They have been developing and perfecting the absorption of horsepower since 1877 and are a world leader in engine and vehicle testing. For more details about Froude Hofmann and information on their testing product lines, please visit www.froudehofmann.com.
Q: What do I need to have in order to do engine testing with a water-brake dynamometer?
A: The basic dynamometer test stand consists of a dynamometer, water supply, a load control valve system (automatic or manual), and a means to collect the data output from the load cell (torque) and the speed sensor (RPM). Other items, such as thermocouples, pressure transducers, and flow measuring devices are “add-ons” that you may not initially need and they’re requirement depends on what type of testing you’re performing. Go-Power Systems allows customers to fully customize their initial system to their primary equipment needs and add items to the system if and when they choose.
Q: What purpose does water serve with a Go-Power Systems dynamometer?
A: Water serves 2 purposes in a water-brake dynamometer application. It provides the means by which “load” (opposing force to the rotation of the engines’ crankshaft) is applied to the dynamometer. Water also carries away the heat generated by the process of absorbing torque, and thus horsepower.
Q: Can I run a water-brake dynamometer on my city water supply?
A: Generally not. City water systems often have inconsistent water supply pressure and variances in delivery volume. These factors contribute greatly to the overall performance of the dynamometer. Typically, the supply pressure from the city is not enough to provide the brake with the amount of water required at its maximum absorption capacity which results in a lack of controllability. Insufficient water supply can also contribute greatly to internal wear of the absorbing elements due to cavitations. Our power curves supplied for each dynamometer model reflect the absorption performance profile of the brake at the minimum water requirement specification for delivery; both pressure and volume.
Q: What are the water pressure requirements for a Go-Power Systems dynamometer?
A: Depending on the Model/Series of the dynamometer you select for your particular application, your water delivery pressure requirement will vary between 45 – 60 PSI or higher.
Q: How much water do I need to run my dynamometer correctly?
A: A typical calculation is that 5.5 gallons of water are required per brake horsepower per hour. For example, in order to run at 200 HP for one (1) hour, you would need 1,100 gallons of water (200 HP x 5.5 gallons of water x 1 hour of running). This water can be re-circulated with the proper equipment. Contact your Go-Power Systems Sales Engineer for details on a semi-closed loop water system.
Q: Do I need to worry about my water temperature?
A: Yes. Go-Power Systems recommends no more than an 80 degrees F inlet water temperature with a temperature rise of 70-90 degrees F depending on the condition of the dynamometer and quality of the water.
Q: What type of water filtration is required for Go-Power Systems water-brake dynamometers?
A: Go-Power Systems recommends a PH level is between 7.4 and 8.4 while maintaining a Calcium Carbonate (CaCO3) level 150 ppm. Suspended solids should not exceed 400 ppm and that the filtration level should be at or below 140 microns. Y-type and Duplex-type strainers are the most common fluid systems and offer the least amount of restriction to flow while providing excellent filtering protection for your dynamometer. Failure to use a filtering device on your dynamometer can result in damage to the internal components, premature failure, and subsequent cost of repairs.
Q: Can I re-use the water through the dynamometer during my test?
First, Go-Power dynamometers must be gravity drained to atmosphere. Therefore, a gravity drain tank is required and a transfer-pump to re-circulate the water back to the supply source. Failure to correctly plumb your water system can result in hydraulic lock, back pressure, and general instability problems.
Q: Can I use anti-freeze or ethyl-glycol for my load water?
A: Anti-freeze and ethyl-glycol are great to use in water brake dynamometers! The use of this fluid can extend the life of the seals and wear of the internals because of its lubricating properties. It also acts as a corrosion inhibitor coating all of the internal surfaces. However, there is an environmental concern that must be taken into consideration. If you intend to use either of these fluids, you must run a semi-closed loop system for obvious reasons. Also, another item to point out is not to exceed a 50/50 mixture of water and one of these two agents due to frothing in the absorption module. Distilled water may also be used in place of your city or ground-well supplied water source for make-up water.
Q: What components are needed for a typical water system?
1. Water Tank: A 250-500 gallon capacity is typical, however the capacity of your tank will be based on what type of testing you’ll be performing (steady state or wide open throttle power runs) and at what power range you’ll be operating. A basic rule of thumb is that it requires more water to absorb more power. The duration of your test(s) will also dictate how much water you will use. Refer to the water flow guidelines described earlier.
Water brake dynamometers require draining to gravity at atmospheric pressure so, if you’re planning on reclaiming your water, you’ll need a gravity drain tank to collect the exhausted load water. You will also need a means to cool that water and a transfer pump to return it to the supply tank.
If a semi-closed loop system is going to be installed, you cannot return the water directly to the supply tank. Remember, you’re using water to absorb the torque output of the engine which is being converted to heat. Therefore, the dynamometer outlet water has to be cooled. This is normally done with an industrial cooling tower designed specifically for this purpose, but depending on application, can be done in a number of other ways. A more economical means would be to either have an intermediate cooling tank where the water can settle and cool to ambient temperature or a series of radiators with electric fans.
Increasing the size of your supply tank will help, but if you’re dumping the hot, effluent water from the dynamometer directly back into the supply tank, your inlet water temperature will continue to rise. This change in inlet temperature will cause the density of the inlet water to decrease which will change the absorption profile of the dynamometer.
2. Booster Pump: A 3-6 hp centrifugal (“flathead”) type is the standard, depending on the model and capacity dynamometer you have. If you’re running additional equipment, such as a cooling tower for the engine, you’ll have to account for the additional water usage. It is always good practice to oversize the water system and its’ components to allow for future upgrades. It is good to start with an 8-10 HP centrifugal pump and increase from there with the addition of ancillary equipment requiring water.
The use of a positive displacement pump is NOT recommended as this style of pump is designed to continue pumping regardless of downstream pressure, meaning that if the control valve is shut and the pump relief valve (a must with the use of this type of pump) fails, the pump will continue to build pressure until the weakest component in the system breaks thereby relieving system overpressure.
The distance between the booster pump/ pressure regulator outlet and the dynamometer inlet control valve should be minimized to ensure the pressure & volume delivered is not affected by the head loss associated with the distance traveled through a piping system. If your pump fails to provide at least the minimum required supply pressure that the dynamometer is designed to operate with, you’ll effectively decrease the absorption capacity of the brake unit.
3. Water Pressure Regulator: Depending on the Model/Series of dynamometer you select for your application, your water delivery pressure requirement will vary. The output pressure of a centrifugal pump is usually pretty steady by design, but the pressure must be regulated to an amount consistent with the power absorption characteristics of your dynamometer. As with just about any machine, water-brake dynamometers have water pressure and volumetric flow-rate specifications that coincide with the units’ optimal performance characteristic. Optimal Performance of a water-brake dynamometer exists when all conditions are met to achieve linear control throughout the power range of the unit. A water pressure regulator, when paired with a sufficient booster pump, will ensure the proper water delivery criterion is met. All water requirements noted on our product data sheets denote the pressure and volume required at the inlet to the load control valve to achieve optimal performance of the dynamometer. The water pressure regulator should be mounted at the outlet of the pump, as close to the load control valve as possible.
4. Load Control Valve: Controlling the amount of water to and from the dynamometer is done by throttling a valve in the inlet and/or outlet to achieve the parameters such as RPM and/or Torque that you’re looking to maintain. Manually operated globe valves, ball valves, butterfly valves, and needle valves are all examples of a good means by which to throttle load water and control a water-brake dynamometer. Valves used in Automatic Load Control Systems are often times Teardrop valves, Spool valves, Plug-cocks, or Stepper Valves. GATE VALVES ARE NOT DESIGNED TO THROTTLE WATER! The design of a gate valve is for ISOLATION only. Attempting to control load with a gate valve will result in a turbulent, non-linear flow profile and erratic behavior and/ or lack of control of the dynamometer. All load control valves should be located as close to the dynamometer as possible, without sacrificing personnel safety. For additional information contact Go-Power Systems for details.
5. Plumbing: The routing of your plumbing is just as important as the equipment you purchase to support your dynamometer test cell. It is always important to minimize joints and bends in the supply line to your dynamometer inlet.
If at all possible, do not mount the pump in a position that it has to draw water up from its supply tank. Should you have an underground tank or the supply tank is located in a different area than the dynamometer, minimize the distance from the supply source to the inlet of the pump. Or, if the supply tank is located outside of the dynamometer test cell, you may find that an additional booster pump will have to be used to satisfy the inlet pressure and volume requirements of your dynamometer.
In a situation where a 90 degree bend must be made prior to entry into a system component such as a pump, regulator, strainer, or valve, ensure that at least 1 foot of straight pipe/hose is installed prior to entry into one of the above mentioned components to allow the turbulent flow created by the rapid fluid direction change while traveling through the bend to dissipate. Flexible, non-collapsible hose may be used to make otherwise sharp bends more gradual and limit the pressure drop normally experienced with the use of cast fittings. PVC can also be used and has a lower head loss characteristic than carbon steel pipe.
Q: What is a ‘Portable Dynamometer’?
A: All of Go-Power Systems’ dynamometer models are portable water-brake units. Portable dynamometers are units that can be installed in virtually any setup because of their small footprint. Go-Power Systems portable dynamometers bolt directly to either the bellhousing of an automotive engine or the SAE housing of diesel engines. Other applications include the use of engine housings with an internal drive coupling and adapter couplings for interfacing our mounting plate with special engine output shafts/drives. Our portable dynamometers can also be used in driveshaft applications and can be fitted for mounting into stationary stands or with the use of our IFA-D2000 diesel dynamometer in-frame adapter, can be mounted within the driveline of heavy duty trucks for in-vehicle engine testing. Go-Power Systems portable dynamometers require no additional support when mounted to an engine! An additional advantage to owning a portable dynamometer is that when your engine testing is completed, they can easily be disconnected and stored until they are called up again for service. Go-Power Systems portable dynamometers are truly the ultimate ‘bolt & go’ solution to all of your testing needs!
Q: How do I determine which dynamometer model and series I need to perform dynamometer runs on my engine(s)?
A: It is important to understand that Horsepower is simply a calculation that reflects the relationship between Torque and RPM throughout the operating range of engines or other prime movers. When determining what dynamometer will support your test criteria, you need to know the peak torque and at what rpm it is developed for each engine you’ll be testing. This data can usually be obtained through the engine manufacturer. Once those parameters are determined, you can draw up a test profile that contains what HP and Torque you’re looking to hold or achieve and at what RPM ranges you expect to see those values. From there, plot out your profile test points on a HP/kW & Torque /Nm vs. RPM graph, also known as a Power Curve. Each series and model dynamometer has a different absorption characteristic and therefore a different Power Curve associated with its abilities. If you have a small engine, say 0-100 hp, you’re most likely candidate will be our D-100 dynamometer model. Most automotive applications and smaller diesel engines will fit into one of the three (3) models in our 57 series dynamometers. Finally, heavy diesel engines will fit the DT dynamometer series. Go-Power Systems Sales Engineers will help you determine which dynamometer will fit your testing requirements.
Q: What kind of maintenance is required on a Go-Power Systems water brake type dynamometer?
A: Maintaining a Go-Power Systems water brake dynamometer is like maintaining any other machine. Greasing of bearings, changing of shaft bearing oil (DT series dynamometers), dead-weight calibration of the load cell to the device where it’s measured, are all examples of ‘routine maintenance’ items.
Q: I recently purchased a used Go-Power Systems dynamometer. I was told that there aren’t many hours on it. How can I check to make sure my dynamometer unit is in good operational condition?
Try to rotate the shaft/rotor assembly by hand. There should be a decent amount of resistance due to the spring pressure of the mechanical seals working against you, but it should rotate over somewhat freely.
Next, turn the unit upside down (with the inlet/outlet fittings pointing up) and support it in this position. Grease all bearing fittings, flushing the old grease out until it is expelled from the bearing races.
Fill the absorption cavity up with antifreeze or ethyl glycol and let it sit for about an hour. The seals, if dry, will expand and the internals will have a nice lubricating coating on them. Try to slowly rotate it again a few times in both directions (remember that all Go-Power Systems portable dynamometers, with the exception of the DT-3000, are bi-directional units). Repeat this step a few times over the course of a day.
If the dynamometer still does not free-up at this point, it may be in need of an overhaul kit and you should contact Go-Power Systems for more information.
NOTE: You must dispose of the antifreeze or ethyl-glycol fluid in a manner consistent with your local environmental protection requirements. This includes flushing the dynamometer several times with clean water to remove residual antifreeze. DO NOT dispose of antifreeze or ethyl-glycol or water contaminated with either of these into a city sewer system or on the ground. Doing so can lead to ground water contamination!
Q: I’m about to purchase a used dynamometer. What do I need to know in order to make an informed decision?
A: Some fundamental questions to ask are as follows:
Q: I have hydraulic load cells as my torque measuring device on my dynamometer. Is there a strain gauge upgrade available for these units?
A: There is a strain gauge upgrade available, however the unit must be sent into Go Power Systems for the upgrade to be performed due to modifications that must be made. Contact Go-Power Systems for pricing.
Q: I want to keep my hydraulic load cell system. How do I interface with a digital console or data acquisition system?
A: In order to interface a hydraulic system to a digital device such as a Go-Power Systems DC-200 console, or a GPS-2508/5000 data acquisition system, a torque transducer assembly must be used. This assembly allows the operator to bleed air from the hydraulic system and interface directly with our torque harnesses. The torque transducer assembly converts the hydraulic pressure to a proportional electronic signal (1-6 volt DC or in certain applications 0-30mv) which is then transmitted to the torque input channel and displayed as a torque reading. Go-Power Systems has an interface kits for every dynamometer model we manufacture that utilizes a hydraulic load cell system.
Q: I am replacing the fluid and/or diaphragms in my load cell assemblies. What kind of fluid should I replace it with and do you still have diaphragms available for my dynamometer?
A: Go-Power Systems recommends the only fluid used for the hydraulic system be Dow Corning 200 silicone fluid. Any other fluid, such as ATF, could contain detergents that chemically attack the diaphragms leading to leaks and/or premature failure. DO NOT EVER USE BRAKE FLUID!!!Load cell diaphragms are available through Go-Power Systems and we manufacture a load cell refill kit for recharging the fluid system.
Note: Care must be taken when replacing load cell diaphragms. To avoid tears and or improper installation, contact Go-Power Systems or refer to the Service Section of your Owners’ Manual. If your diaphragms have failed, the most likely cause, if not age or improper fluid, was improper installation.
|
| Products | ||||
|---|---|---|---|---|
|
