Respirometer Systems and Applications, LLC

- Model PF-4000 and PF-8000 - Pulse-Flow Respirometers


RSA’s PF-4000 and PF-8000 Pulse-Flow respirometers are designed specifically to measure oxygen uptake for aerobic biological reactions and gas production from anaerobic and anoxic biological reactions. Modular system design allows easy expansion. The 8-position PF-8000 units can be expanded easily to 16 and 24-position units. The 4-position PF-4000 units can be expanded to an 8-position system.

Mode of Operation: When operating in the aerobic mode, oxygen – from a supply of pure oxygen – is added in small increments into each respirometer vessel in response to oxygen uptake and carbon dioxide absorption. This mode of operation maintains a constant oxygen concentration in the headspace within the reaction vessel. Oxygen transfer from the headspace to the liquid phase is accomplished by using magnetic stirring units having high mixing rates. When operating in anoxic or anaerobic modes, gases produced by biological reactions flow into an internal storage chamber and are released when a pre-set pressure buildup is detected by a pressure transducer. These incremental volumes are carefully controlled through accurate calibrations established by RSA.

Number of Reactors: 4, 8, 16, and 24-position system are available. Four-position systems can be expanded to 8 positions with the addition of an internal expansion module. Eight-position systems can be expanded to 16 and 24-position systems with addition of satellite flow-control modules. All units of a system are connected to a single computer for data acquisition.

Operating Mode: All standard Pulse-Flow respirometer systems can be operated in aerobic or anaerobic modes without the need to purchase separate control modules or complicated hardware. Anaerobic-only or aerobic-only systems are available on request.

Stirring Base: The RSA-4000 and RSA-8000 stirring bases are designed and constructed with the following features:

  • Individual or simultaneous speed control
  • Stirring speeds up to 1,500 rpm
  • Minimal heat generation
  • Stainless steel cabinets to eliminate corrosion
  • Welded joints to eliminate water damage.

Data Acquisition: Oxygen uptake or gas production pulses are registered by computer. The data are filed as cumulative oxygen uptake when operating in the aerobic mode or as gas production when operating in the anaerobic mode. The software is available for 4, 8, 16 and 24-reactor systems and operates in the Windows™ graphics software environment. Data acquisition is independent for each reactor. The data are filed in a convenient format for subsequent processing or mathematical model.

Modular Design: Independent cabinets for control modules and stirring bases allow maximum flexibility in use of laboratory counter space. The control modules for 16and 24-position Pulse-Flow systems can be operated together or independently. Individual 8-position control modules can be operated at different temperatures or test conditions if desired or one module can be operated aerobically while another is operated anaerobically. Individual control modules can be operated for combined or individual data acquisition.

Temperature Control: Pulse-Flow respirometers can be used in constant temperature incubators, or optional water baths and heating/cooling units are available from RSA.

Reaction Vessels: Except for a few specialty items, Pulse-Flow respirometers use standard glassware and supplies that are available from most chemical supply companies. Standard bottles accommodate 500 mL sample volumes. Bottle sizes can vary from 250 mL to 2 L depending on test objectives.

Sensitivity: The lowest increment of oxygen uptake is 0.05 mg. The highest oxygen uptake rate for the standard system configuration is 1,200 mg/hr. Rates can be increased more than 10-fold by adding simple plug-in flow expansion modules. These high rates are useful for monitoring oxygen uptake in large laboratory-scale pilot units.

System Specifications

  • 4, 8, 16, and 24-position flow measuring capacity
  • Stainless steel cases for control modules and stirring bases
  • Standard accessories include: 500 mL reaction vessels with caps and septa; tubing, carbon dioxide absorption inserts, and essential supplies needed for startup.
  • Optional stainless steel water bath
  • Optional heating/cooling unit for temperature control in water baths
  • Electrical: Low-voltage 12 VDC power supply for both the control module and stirring base.

Operational Specifications:

  • Minimum oxygen uptake = 0.05 mg
  • Maximum oxygen uptake > 1,200 mg/hr (expandable to 12,000 mg/hr or greater)
  • Minimum gas flow = 0.04 mL
  • Maximum gas flow rate > 1,000 mL/hr (expandable to as high as 10 L/hr)
  • Operating temperature: 5 to 70oC
  • Sensitivity: < 0.05 mg (aerobic), < 0.04 mL (anaerobic)
  • Precision: < 3% CV aerobic and anaerobic
  • Warranty: 1 yr against mfg defects (except expendable supplies)

Computer Specifications:

  • Desktop, tower or laptop can be used
  • Pentium 233 or higher is suitable
  • Windows NT, 2000, XP or Vista compatible
  • USB port required for data acquisition

Installation: All purchases of 8 to 24 –position Pulse-Flow respirometers include installation and start-up training. RSA’s application specialists are available by email or telephone for three months after installation to assist users with operation and application of their unit. Additional assistance with operation and application – including on-site consultation – can be purchased on short-term or long-term care arrangements. Installation and training are optional for 4-position systems.

Leasing and Rental: Pulse-Flow respirometer systems are available on a lease-purchase option whereby payment can be made over 12 to 24 months. Assistance services via email or telephone are included for the duration of the lease. Pulse-Flow respirometers also are available for rental on a short-term basis.

Additional Features

  • No special oils are required for operation, thereby avoiding spills and inconvenient cleanups
  • No grease is required to seal the reaction vessels, thereby eliminating messy cleanup.
  • Flexible operation. The modular design helps to optimize counter space

  • Biodegradation Assessments
  • Activated Sludge Respiration (ASR) Tests
  • OUR Fingerprinting (OUR Respirograms)
  • Biomass Activity Tests
  • Extant Kinetic Measurements
  • Performance Evaluations
  • Toxicity Assessments
  • Short-Term BOD Measurements

RSA’s PF-4000 and PF-8000 Pulse-Flow respirometers are designed specifically to measure oxygen uptake for aerobic biological reactions and gas production from anaerobic and anoxic biological reactions. Modular system design allows easy expansion. The 8-position PF-8000 units can be expanded easily to 16 and 24-position units. The 4-position PF-4000 units can be expanded to an 8-position system. Oxygen uptake is measured at rates as low as 0.05 mg/min and as high as 1,200 mg/hr. Units can be used in a constant-temperature incubator or can be fitted with optional water bath and heating/cooling units.

Accuracy and Precision
High accuracy and precision are accomplished through quality design and construction. Each system is factory-calibrated to ensure accuracy.

Collection Data
Oxygen or gas flow data are monitored by computer and stored in convenient spread-sheet format for ease of data evaluation. The PF Systems software was designed for user convenience and provides on-screen tabular and graphical indications of the cumulative oxygen uptake and gas flow rates. Data record intervals can be set at intervals ranging from 1 to 720 minutes.

The operation of PF respirometer systems is simplified through the use of standard laboratory glassware. No grease or specialized lubricants are required to seal the reaction vessels, thereby reducing the set-up and cleanup time. Gas or liquid samples can be withdrawn easily from reaction vessels at any time during a test.

PF respirometers allow maximum flexibility in application. Operation in the low-flow mode provides maximum sensitivity for monitoring low-rate aerobic or anaerobic reactions. Operation in high-flow modes allows measurement of oxygen uptake or gas production for large laboratory-scale pilot plants at rates in excess of 360 mL/hour. Reactor volumes for normal respirometric applications are 500 mL, but can range from less than 50 mL to 2 L or larger.

Equipment Items

  • 4- or 8-position flow measuring base
  • USB output to any computer for data acquisition*
  • Accessories kit
  • 4 or 8-position magnetic stirring base
  • Readout interval (1 to 720 minutes)
  • Electrical requirements (110 to 240 VAC, 50-60Hz)


  • Reaction vessel size (50 mL to 2+ L)
  • Temperature of operation (5 to 70OC)
  • Minimum flow rate detection: < 0.05 mg O2
  • Maximum flow capacity: ~ 360 mg O2/min
  • Sensitivity: as low as 0.05 mg
  • Measurement precision: < 3% CV

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