The Fully Automated Arthur
Phase V  Respirometer
with updated electronics, single or double units, and with the same
unique features that have always set it apart from all other
wastewater respirometers.

                   Double Unit Arthur Respirometer in Waterbath 
                    Model #028-202  Phase V
. Same vigorous airlift mixing as
in a full scale activated sludge plant

. Never a shortage of air supplied
during testing. Oxygen transfer
superior to any other repirometer.

. Never a need to dilute or filter
high solids samples

. Instrument ready to begin testing
upon startup. Test results in minutes.

. 2-liter sample chambers test large,
truly representative samples.


Specification sheet

 PHASE V  Fully Automated Arthur
Bench Respirometer

Single Unit Arthur Activated Sludge Respirometer in Waterbath

             Model No. 028-201 Phase V


Features of the Arthur
Automatic Respirometer

.  Aerobic or anaerobic test capability
.  Single or Dual test chambers
.  Waterbath for temperature control
.  Atmospheric pressure compensation
.  No limit on oxygen supplied to test chambers,
   air comes directly from atmosphere as needed
.  Vigorous Airlift Mixing prevents settling,
   permits testing of high solids samples without
.  Excellent oxygen transfer
.  Modular construction for easy cleaning,
   replacement of parts.
.  Continuous graphic readout of changes in respiration
.  On-board computer with touch screen controls
.  Tests liquids, solids or slurries
.  No contact between sensor and sample

Operation Principle
The Arthur Activated Sludge Respirometer is available with single
or dual test chambers within a waterbath tank. Each measuring
device utilzes a combination of sample chamber, carbon dioxide
scrubber, sensitive gas volume transducer, air reservoir and foam
trap, air pump and automatic gas exchange system.  The latter
four are located in separate sealed compartments that can be
easily disconnected and replaced if necessary.  The air pump
provides continuous air circulation through the sample chamber
and the scrubber.The entire air system is closed to the atmosphere.
As the specimen in the chamber utilzes oxygen and generates
carbon dioxide, the carbon dioxide is immediately removed by the
caustic solution in the scrubber.  The volume of carbon dioxide
produced is therefore not present to balance the volume of oxygen
utilized, and there is a net loss of gas volume equal to the volume
of oxygen utilized.  The change of gas volume is sensed by the gas
volume tranducer.  The transducer converts the volume of oxygen
used to an electrical signal which is fed to a computer.  The
instrument produces a continuous graphical record of respiration.
It can also be used to measure volume of gas produced, as in
anaerobic processes.

Each Arthur Bench Respirometer consists of five main components:  

1.  Sample chamber

2.  CO
2 Scrubber chamber        

3.  Respirometer module

4.  The Waterbath

5.  Electronics cabinet with Touch Screen & On-board Computer

The Sample Chamber, CO2 scrubber and Respirometer module are connected to each other with tubing and quick disconnects. 

Sample Chamber...The instrument is normally furnished with a two-liter cylindrical chamber, but various sizes  and shapes are available. On the removable top of the Sample Chamber is a fill tube closed with a threaded plug.  The plug is fitted with a syringe connector for calibration.  Sample Chambers can be removed and disassembled to clean.  When installed, each Sample Chamber is connected to a valved drain.  With liquid samples the chamber utilizes an airlift pump to aerate and mix the sample.  Air is distributed at the base of the airlift column through a fine bubble diffuser.  Solid samples are usually placed on a porous stage and the air flows up through the stage.

Respirometer Module...This rectangular shaped module is located behind the Sample Chamber and CO2 Scrubber Chamber in the waterbath. It consists of an assembly frame with volumetric transducer box attached, an air reservoir and foam trap, an automatic gas exchange system box and an air pump box.  The air reservoir and foam trap, gas exchange system box and the air pump box can be easily removed from the assembly frame.  A drain is provided to remove the oil from the volumetric transducer.

Water Bath.... Respiration tests can be performed at a full range of temperatures using the waterbath.  The water in the bath completely covers the
respirometer module, sample chamber and CO
2 Scrubber.  Temperature control can be obtained by using an Immersion Heater in the waterbath. Cooling can be provided with an Immersion Chiller. 

The Electronics Module...All controls to operate the respirometer are contained in the electronics module.  This includes a power switch with indicating light, on-off switches for atmospheric pressure compensation, automtic venting and zero and span adjustment controls.


The respirometer is calibrated by withdrawing a prescribed amount of air with a calibrated syringe.


Model No............................................028-201 Phase V Single

Model No..........................................028-202 Phase V Double

.  Sample Chamber (2-Liter): Inside, 4"D x 13"H
   Other sizes available:

.  Respirometer Module - Outside 4" W x 7 7/8"D x 15 7/16"H

.  CO2 Scrubber - Inside 2 1/2"D x 13"H

 Net Weight ................................110 pounds (Double Unit)

Shipping Weight........................116 pounds (Double Unit)

Air Pump..............Pumping rate: 2000ml/min at 1 ft. Head

Air Capacities...............................3000 ml without venting

Range of total oxygen demand.........................not limited

Power Source...90-260 VAC, 47-64 HZ 55 watts max. ea

Internal Components..........................Solid State Circuitry

Output Signal...................0-10 millivolts - analogue signal

Precision.................+ 2% as measured with sodium sulfite

Maximum Waterbath Operating Temperature............35oC

Warranty...Fully warranted against manufacturer’s defects for Eighteen months
except the Echopod which is warranted for 12 months.

Patent...Arthur Respirometers are patented under one or all of the
following patents: 3,348.409; 3,740,320; 4,314,969; or 4,650,767.
Other patents are pending.

Single      Double

333-025   333-225  Anaerobic Conversion Kit

333-026   333-226  Set of perforated stages for solid samples

050-550    Immersion Heater (120V)

050-551    Immersion Heater (240V)

070-850    Immersion Chiller (120V)

 Telephone Toll Free in US and Canada: 1-800-328-7518 or 920-922-6970    

FAX: 920-922-1085

  Email Address:
Mailing Address:
PO Box 1236, Fond du Lac, WI  54936-1236  USA
Shipping Address:
114 South Main St. Fond du Lac, WI   54935,  USA


Distributors are being sought for the Arthur Respirometers
in Asian and Latin American countries.  Distributors must
have in-depth knowledge of the activated sludge process.

 Toll Free in USA & Canada   1-800-328-7518
             920-922-6970     Fax:  920-922-1085
  Site Map