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Dual-Seal-Pump-Square-1
Pumps

Dual Seal Variable Volume Precision Dispense Pump

Dual-Seal-Pump-Square-1
Dual-Seal-Pump-Square-1

This stepper motor-driven positive displacement pump is engineered to reliably control more challenging fluids, including those with high concentrations of surfactants and fluids prone to crystallization, across an extensive cycle life. It utilizes two seals and two fluidic chambers to isolate the motor from the working fluid. The portion of the piston in contact with the working fluid does not retract past the second seal, and the isolation chamber can be plugged with air, filled with a barrier fluid, or actively flushed to dilute fluid residue on the piston. All designs are equipped with a home sensor to establish the end of stroke and an optical motor encoder to provide feedback on piston movement.

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Key Product Facts
  • Full Dispense Volumes:500 & 1000 µL
  • Highly Precise:CV ≤0.03%
  • Home Sensor & Encoder Included on Every Pump
  • Integrated Backlash Compensation
  • Port Head Material Options: PMMA or PEEK

Product Information

General Specifications
Characteristic Specification
Max Dispense Speed1 2000 Full Steps Per Second
Self Priming Pumps Operate Across a Wide Pressure Range
Max Discharge Pressure2 30 psig
Operating Temperature 40°F to 150°F (4°C to 66°C)
Storage Conditions3 Temperature: -40°F to 175°F (-40°C to 80°C)
Relative Humidity: 85% Max, Non-Condensing
1Operating the pumps at higher speeds may affect dispense accuracy and life expectancy. The pumps may be operated in full-step, half-step or micro-step mode, depending on the electrical drive design and application parameters. Refer to the individual pump's inspection drawing for additional specifications such as harmonic frequency, etc.
2Varies by pump model. Refer to the part number table for individual pump specifications.
3Pumps should be stored completely wet or completely dried with nitrogen before prolonged periods of inactivity.
Wetted Materials
Component Material
Port Head Chamber Port Head: PMMA or PEEK
Piston: TZP
Primary Seal: UHMWPE
Seal Isolation Chamber Chamber: PEEK
Piston:TZP
Primary Seal: UHMWPE
Secondary Seal: UHMWPE & 316 Stainless Steel
Electrical Operation
  • Pumps are equipped with a NEMA 17 bipolar stepper motor
  • Home sensors provide a 5 V end of stroke indication; the sensor output will remain low (0 VDC) when the piston is fully extended.
  • Rotary encoders are two-channel, quadrature (no index pulse) designs.
Velocity Profile
Using the maximum recommended speeds, the variable volume pumps can complete one full aspirate and dispense cycle in the time indicated in the table below. Depending on use conditions, it may be possible to drive the pumps faster. Other applications may require slower operation to prevent motor stalling or fluid cavitation.
Cross Section View
Full Isolation Dual Seal Model
Dimensional View
Full Isolation Dual Seal Model
This image is for reference only. All dimensions are in inches [millimeters].
Mounting & Fluidic Connections
There are four ¼-28 flat bottom ports per pump: two in each chamber. The Dual Seal Pump utilizes two seals to isolate the motor from the working fluid. The range of piston movement is shorter than the spacing between the primary and secondary seals, which guarantees no part of the piston in contact with working fluid will ever retract past the second seal. Between the two seals is the seal isolation chamber, which can be used in various ways to prevent crystallization and dilute working fluid residue on the piston. The simplest method is to plug this chamber and leave it full of air. This limits the evaporation of the working fluid residue on the piston, reducing the buildup of harmful crystals. The chamber can also be filled with a barrier fluid and plugged. This prevents crystallization and dilutes surfactants, which eliminates leakage. In the most extreme cases, the seal isolation chamber can be actively flushed with liquid, consistently diluting the working fluid while washing the piston and primary seal.

Get Started

Are you ready to get started? The Lee Company’s Variable Volume Pump (VVP) Driver (part number LSWX0307810A) is driven by the powerful Trinamic TMC5130 motion controller and motor driver, along with two Trinamic MAX22200 solenoid drivers. This comprehensive setup empowers the driver to effortlessly manage every aspect of the pumping system, from the precise control of the bipolar stepper motor, home sensor, and encoder to the management of two solenoid valves. The driver is optimal for expediting benchtop testing of Lee pumps and valves. The I2C and UART comms options also allow the driver to be integrated into end systems, streamlining system development. Crafting custom scripts and subroutines is a breeze with the TMCL IDE, allowing users to easily upload code to the driver for standalone operation. Moreover, the driver can function as a peripheral device, seamlessly receiving direct motion commands from another controller. For newcomers, a library of starter scripts is readily available to assist with simple pumping routines. Additionally, for those seeking advanced control options, a detailed firmware manual is available to get optimal performance for your application. See below for downloadable reference files and contact a Lee Sales Engineer for more information.

Part Numbers & Specifications

This table below contains the part numbers and technical specifications for this product. If you have specific questions, need a quote, or would like to request a handbook or drawing, click the red request button in the column on the far right.

Part Numbers & Specifications
PART NUMBER FULL DISPENSE
VOLUME
(µL) 		FULL STEP DISPENSE
RESOLUTION
( µL/STEP) 		MAX SPEED
(FULL STEPS
PER SECOND) 		PRECISION: CV
10% TOTAL
DISPENSE VOLUME 		PRECISION: CV
100% TOTAL
DISPENSE VOLUME 		DISPENSE ACCURACY
AT 100%
DISPENSE VOLUME 		PORT HEAD
MATERIAL1 		HOME SENSOR ENCODER INTEGRATED
BACKLASH
COMPENSATION 		Request Information
LPVA1725350D 500 0.469 2000 ≤0.3% ≤0.03% ±0.5% PMMA Yes Yes Yes Request
LPVA1755350D 500 0.469 2000 ≤0.3% ≤0.03% ±0.5% PEEK Yes Yes Yes Request
LPVA1725310H 1000 0.4 2000 ≤0.3% ≤0.03% ±0.5% PMMA Yes Yes Yes Request
LPVA1755310H 1000 0.4 2000 ≤0.3% ≤0.03% ±0.5% PEEK Yes Yes Yes Request
1Port head material varies by part number as described. The seal isolation chamber is PEEK on all models. Customized port heads are available upon request and may include alternative materials, valve mounted directly to the port head, or different fluidic ports.

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From plugs to solenoid valves, there’s a vast array of products that The Lee Company can offer. If you’d like to discuss the best solution for your specific application or to learn more about our capabilities, use-cases, or quality standards, contact your local Lee sales engineer.

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The Lee Company has developed the Lohm Laws for defining and measuring resistance to fluid flow. The Lohm is defined such that 1 Lohm will flow 100 GPM of water with a pressure drop of 25 psi at a temperature of 80°F.

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