A Quarterly Newsletter of Parr Instrument Company | December Edition 2015 | Vol. 2 No. 4
Welcome to ParrNotes
Welcome to our last edition of ParrNotes for 2015. It’s hard to believe another year has slipped by. It’s proven to be a challenging global market this year. Low energy and commodity prices, strong dollar, sluggish global growth, and geopolitical issues around the world have all contributed. These cycles never last, and new research and development must always go on if the world is going to grow and meet tomorrow’s challenges. Parr will be there to provide solutions to your customers research needs.
I want to take this opportunity to thank all of you for your continued dedication and hard work this past year. A strong partnership between Parr and its dealers like you, is the key to providing world class sales and service that makes us a world leader in what we do. We couldn’t do it without you, and for that we are grateful. We enter 2016 with wishes of peace, prosperity, and good health in the year to come.
President & Chief Operating Officer
Features and Benefits
Parr Custom Calorimeters
Parr is a distinctive calorimeter producer in the market. It is well known that a large portion of Parr’s business is custom built reactor systems. However, few know that Parr builds custom calorimeters for special tasks as well.
Recently, in response to a customer request, Parr developed a high strength combustion micro-vessel 1109X, with the corresponding bucket, for use in a 6200 Calorimeter. This system is optimized for applications where samples have a small energy release but generate high dynamic pressure during the combustion. This system is additionally optimized for scenarios where the amount of sample available for testing is limited. This special version of the Parr 6200 Calorimeter and 1109X Vessel performs with better than 1% precision for energy releases as low as 1 kJ (equivalent to 40 mg of benzoic acid). This arrangement provides superior precision in the low energy range for combustion or reaction processes which is generally unattainable with calorimeters using conventional size vessels. This calorimetric system is especially useful in applications where the determination of the heat of combustion is required for optimizing the chemical synthesis of energetic materials, or similar research tasks.
Parr welcomes customer challenges and always looks forward to meeting them.
Let us build one for you.
DC Motor Drives used with Stirred Parr Reactors
Parr has used simple Silicon Controlled Rectifier (SCR) drives to power DC type stirrer motors for many years. This article will briefly describe how these drives work to aid in the troubleshooting of potential drive related issues.
Essentially, an SCR drive uses fast electronic switching to modify the incoming AC sine wave providing a regulated DC output. Due to the nature of this switching method the DC output is fairly choppy. The Permanent Magnet DC motors (PMDC) that are provided with stirred Parr reactors are appropriately rated for such drives. These drives can also be used with some shunt wound DC motors as well as universal DC/AC motors.
115 Vac drives are typically used for 90 Vdc motors and 230 Vac drives are typically used for 180 Vdc motors. Parr’s smaller motors are not available in 180 Vdc, so specially configured drives are used to output 90 Vdc when using a 230 Vac input.
Drives configured to power 180 Vdc motors are provided with time-delayed fusing to protect the motor in case of over-loading. Drives configured to power 90 Vdc motors are provided with circuit breakers to protect the motor and drive. A fuse sizing chart can typically be found in the associated controller manual.
230 Vac drives are provided with additional fusing at the drive. A 10 amp fast-acting fuse is provided on the input of the drive to protect the incoming power circuit. An 8 amp very fast-acting fuse is provided on the output to protect the drive. Abruptly switching power on to the motor can cause the 8 amp fuse to blow. It’s recommended that the manual speed control be slowly increased until the desired stirring speed is reached and to ensure that PI controllers are not sending an output signal when the motor is initially powered.
Parr’s 4-pin motor output connector is configured in such a way that helps prevent an incorrect motor from being plugged into the controller. The most common configurations (90 Vdc and 180 Vdc) are below.
180 Vdc Drives
Pin 1 – 0-180 +Vdc
Pin 2 – Ground
Pin 3 – 0-180 Vdc return
Pin 4 – Keyed
90 Vdc Drives
Pin 1 – 0-90 +Vdc
Pin 2 – Ground
Pin 3 – Keyed
Pin 4 – 0-90 Vdc return
Note that a portion of the AC line to neutral (ground) voltage can be measured at either of the motor output pins whenever the drive is powered.
The speed control boards have several trimpots that have been factory set. Descriptions of these adjustments can be found below. For adjustment procedures please contact Parr’s technical support staff.
Acceleration Trimpot (ACCEL)
The ACCEL trimpot can be used to set the acceleration time of the motor in seconds.
Maximum Speed Trimpot (MAX)*
The MAX trimpot can be used to set the maximum speed (voltage) supplied to the motor when the speed adjustment pot is rotated fully clockwise.
Minimum Speed Trimpot (MIN)*
The MIN trimpot can be used to set minimum speed of the motor (0 rpm) when the speed adjustment pot is fully counter-clockwise.
*Note that when either the MIN or the MAX trimpots are adjusted, they can affect the setting of the opposing trimpot.
Current Limit Trimpot (CL)
The CL trimpot can be set to limit the maximum current to the motor, which is typically about 130% of the motor’s rated current. This adds additional protection to the motor and limits the inrush current to a safe level during startup.
IR Compensation Trimpot (IR)
The IR trimpot is used to improve load regulation. When using the manual speed control knob, the IR Compensation allows the motor to remain at a constant speed during slight variations of the load. Note that this circuit should be disabled when monitoring changes in the stirring load in a closed loop control scheme, which can be done by turning the IR trimpot fully counter-clockwise.
Two troubleshooting LED’s can be found on the speed control board. The “PWR ON” LED will be lit when AC line power is applied to the board. THE “CL” LED will be lit if the current limit circuit is active indicating an excessive load.
We hope that this information will aid you in understanding and troubleshooting of the DC drives found on most of Parr’s stirred reactors. If you have any questions, please contact Parr’s technical support staff.
Motor Troubleshooting Flow Chart
Motors are a major component of Parr Reactor Systems that are managed by controllers. Many factors can lead to motors not working properly. To help navigate through these factors, we have put together a flow chart for troubleshooting a non-functional motor.
Click here to download a pdf version of the Parr Motor Speed Control Flowchart.
Drain Valves for Parr Reactors and Pressure Vessels
What is the difference between a “Bottom Drain Valve” and a “Drain valve in the bottom”?
The Parr “Bottom Drain Valve” is designed with a valve stem or plunger that protrudes up to the inside bottom of the vessel so as to form a nearly flush bottom to the inside of the vessel cylinder. These are often referred to as a BDV.
A flush-bottom drain valve can be very important when, for example, one is stirring a reaction that involves a powdered catalyst. It would not be advantageous to have a dead spot in the bottom of the vessel which could collect the powders, effectively removing them from the reaction. Reactors being used to make solid particles, such as polymerization reactions and nano-particle formation, may similarly benefit from the use of a flush-bottom drain valve. Note that when the valve is closed, the valve stem cleans the internal port as it moves back upward.
However; on the other hand, reactions that do not have powders may not require the more expensive BDV and can be adequately served with a “drain valve in the bottom.” In these cases, a stand-off or nipple is added to the bottom of the cylinder extending below the heater to where a metering valve is attached. Note that there will be a dead space at the bottom of the cylinder down to the shut-off valve. One additional advantage of the “drain valve in the bottom” is that this arrangement can be used to sample materials from the vessel while it is under high pressure. The Parr “Bottom Drain Valve” (BDV) is not to be operated under pressurized conditions. These valves are for draining, not for sampling.
Parr Team Member Focus
Bert Ellis, Product Designer
Bert was born and raised in Chicago, Illinois and now resides in Andalusia, Illinois. While in Chicago, he earned his A.A.S. in Electronics from Wright Jr. College. He went on to earn his B.S. and M.S. in Industrial Technology from Western Illinois University in Macomb, Illinois.
Bert will be celebrating his 20 year anniversary at Parr Instrument Company in 2016. As one of Parr’s Product Designers, Bert uses CAD software to design and detail parts and assemblies for Parr’s many custom orders. Bert also helps process the Bills of Materials for custom orders as well as provide support for the Sales and Engineering Departments.
Some of the highlights that have kept Bert at Parr over the years are the friendly working atmosphere, the satisfaction that comes with turning a customer’s unique request into a workable design, and the knowledge that Parr’s products benefit so many people all around the world.
December 15-20, 2015
Hilton Hawaiian Village, Honolulu, Hawaii
Look for Parr U.S.A.
Send us your 2016 Trade Show Schedules
We are currently compiling our 2016 Trade Show Schedule. Please send us a list of any shows where you will be representing Parr at in 2016, so we may add them to our Trade Shows page.