Dry Gas Meter Research Articles

William Richards and the Unrecorded Success Abroad: A British Engineer in the Spanish Gas Industry in the Nineteenth Century

In the middle of the nineteenth century, the British engineer William Richards made an important contribution to the introduction of the gas industry in Catalonia, Spain. Following his development of the dry gas meter, but failure to create a commercial business from it, Richards sought to re-establish his reputation away from the crowded British Gas industry to go in search of new horizons abroad. In 1848, he became the engineer at the Gasworks in Barcelona. Between the years of 1851 and 1859, Richards directed the construction of several gasworks in Catalonia. This paper examines the significance of Richards’s achievements, both in England and Spain during the period from 1843 to 1893. Whilst sometimes unrecognised in his country of origin, this paper demonstrates that he was an active innovator, gas engineer and an early exponent of international technology transfer in the gas manufacturing industry.

Application of a Dry-Gas Meter for Measuring Air Sample Volumes in an Ambient Air Monitoring Network

Ambient air monitoring for non-research applications (i.e., compliance) occurs throughout the world. Often, air sampling systems employed for these purposes employ simple yet robust equipment capable of handling the rigors of demanding sampling schedules and harsh environments. At the Hanford Site (near Richland, Washington) concentrations of radionuclides in ambient air are monitored continuously at 44 locations. In 2004, mechanical dry-gas meters were incorporated into the Hanford Site ambient air sample collection system to allow the direct measurement of sample volumes. These meters replaced an airflow measurement system that required two manual flow measurements and a sample duration measurement to determine sample volume. A six-month evaluation of the dry-gas meters compared sample volumes calculated using the original flow-rate method to the sample volume measured directly by the dry-gas meter. The two methods provided sample volumes that were within 15% of each other 87% of the time. The results indicated that for instances where the sample volume measured by the two methods differed by more than 15%, the dry-gas meter method provided a more accurate sample volume measurement. The results of the evaluation further indicated that the dry-gas meters provided more accurate sample volumes for all samples, resulting in greater confidence in the calculated concentration results.

Gravimetric and analytical evaluation of welding fume in an automobile part manufacturing factory.

Welding is one of the most exercised industrial processes which welders are exposed to chemical and physical Hazardous agents. This study was conducted to evaluate occupational and environmental exposures to aerosols generated by welding processes in a factory. A total of 28 samples of aerosols were collected at 4 different locations including indoor, outdoor, source of welding and the stacks using a high volume pump with a volumetric flow rate of 112 lit/min calibrated with a dry gas meter. The samples were collected on round 110 mm fiber glass filters, measured gravimetrically, extracted using nitric acid and analyzed with atomic absorption spectroscopy method for heavy metals including Fe, Mn, Ni, Cr3+, Cr+6, Co, and Zn. Gravimetric measuring has shown the mean values of indoor air: 1.33 mg/m3, breathing zone of the welders using coated electrodes and CO2: 7.25 mg/m3 and 6.45 mg/m3 respectively and in ventilation exhausts: 95.07 mg/m3. The mean values of Fe, Mn, and Ni were 0.8, 0.041, and 0.00 mg/m3 in indoor air, 2.7, 0.18, and 0.15 mg/m3 in breathing zone of welders used coated electrodes, and 1.75, 0.08, and 0.22 mg/m3 in breathing zone of welders used CO2 welding respectively. The concentrations of Cr3+, Cr+6, Co, and Zn were too low to be detected. The welders were exposed to high concentration of metallic fumes, which raise the risk of pulmonary dysfunction and other health disorders. Using suitable respiratory masks and Appling the effective local ventilation system may improve the working condition.

PROLONGED EXERCISE TRAINING DURING HEAD-DOWN TILT BEDREST PRESERVES UPRIGHT EXERCISE CAPACITY

Adaptation to real or simulated microgravity leads to a reduction in maximal exercise capacity in the upright position. Although exercise training in space or during bedrest may preserve supine work capacity, few sustained interventions have successfully maintained upright exercise capacity. Hypothesis: We hypothesized that exercise training sufficient to normalize cardiac work and prevent cardiac atrophy would also preserve upright exercise capacity. Methods: We studied 17 subjects (14 men and 3 women, age 25–48 yr) before, during, and immediately after 18 days of bed rest. The subjects were divided into two groups: (1) bedrest without exercise (n = 5) and (2) bedrest with 90 minutes/day of supine cycling exercise (n = 12) at 75% max HR calculated to normalize cardiac work compared to freely ambulatory periods. VO2max was measured before and after bed rest with an incremental protocol on an upright cycle ergometer at 30W/min until exhaustion. We measured gas fractions by mass spectrometer, ventilation via dry gas meter for the calculation of VO2 (Douglas bag method) and heart rate via electrocardiogram (Polar). Results: VO2max of subjects who trained during bedrest was maintained at pre-bedrest levels (2.93 ± 0.82 vs. 2.79 ± 0.70 L/min p = n.s). However, VO2max of nonexercising subjects decreased by 25% following bedrest (2.67 ± 0.52 vs. 1.99 ± 0.47 L/min p < 0.05). This differential response between the 2 groups was highly significant (2-way ANOVA interaction p = 0.004). Upright maximal work rate was preserved in the training subjects (217 ± 52 vs. 217 ± 49 Watts) but reduced in the sedentary subjects by 14% (206 ± 42 vs. 178 ± 25 Watts, interaction p = 0.08). Conclusions: Upright work capacity and VO2max are maintained in subjects who perform 90 min/day of dynamic exercise during HDT bedrest.

PREDICTING THE ENERGY COST OF WALKING IN OLDER ADULTS 985

The purpose of this study was twofold: to evaluate the ACSM prediction equation for energy cost of walking in older adults, and to identify predictors of the energy cost of walking in older adults. Twenty one attendants of the NY State Senior Games (8 males, 13 females, aged 55 to 75 yr) walked for a minimum of seven minutes at 80.4 m·min-1 (3 mph) on a motorized treadmill. Oxygen consumption (VO2 in ml·kg-1·min-1) was measured using an on-line gas analysis system (Ametek O2 and CO2 analyzers and Vacumed dry gas meter interfaced with a computer). Heart rate (beats·min-1) was monitored by a Polar Vantage XL heart rate monitor. Respiratory exchange ratio and caloric equivalent were used to convert VO2 in liters·min-1 to kilocalories·min-1. Average values for the last three minutes of exercise were used for data analysis. A paired t-test was used to determine that the actual VO2 (14.8 ml·kg-1·min-1±2.0) was significantly higher than the ACSM predicted VO2 (11.5 ml·kg-1·min-1) (t= 7.6, p<.0001). Stepwise regression (F-to-enter = 4.0, F-to-remove = 3.996) was used to examine body mass (kg), heart rate (HR), and sex (males = 0, females = 1) as predictors of the caloric cost of walking at 80.4 m·min-1. Each variable significantly contributed to the final equation: caloric cost(kcal·min-1) = -1.008 +.057 (mass) +.024 (HR) -.917 (sex). Mass was the strongest predictor of caloric cost (R=.886; F = 69.1, p<.0001). Heart rate entered the equation second (R =.916; F=47.0, p<.0001) and sex third with a final R of.945 (F = 47.7, p<.0001) accounting for 89% of the variance in the caloric cost of walking at 80.4 m·min-1. In conclusion, the ACSM equation did not provide an accurate estimation of the energy cost of walking on a horizontal treadmill for these older adults. Body mass, heart rate response to walking, and sex appear to provide a reasonable estimate of the energy cost of walking at a moderate pace in older adults.

Morphine-6-glucuronide: effects on ventilation in normal volunteers

The respiratory responses to intravenous morphine sulphate (0.12 mg/kg), morphine-6-glucuronide (M6G; 0.03 mg/kg) and placebo were assessed in 6 healthy volunteers, using a single blind randomised crossover design. Five of these subjects underwent an additional study of M6G at 0.06 mg/kg. Respiratory rate, minute volume and end-tidal CO 2 were continuously measured using a low resistance non-rebreathing circuit, a mass spectrometer and a dry gas meter. The ventilatory responses to CO 2 exposures (5.5% for 4 min) were assessed 40 and 20 min before, and 20, 40 and 80 min after drug administration. Following placebo and M6G (at both doses) no change in end-tidal CO 2 occurred whilst the subjects were breathing air, whereas following morphine a significant rise was seen ( P < 0.05). Morphine reduced the ventilatory response to 5.5% CO 2 at all times tested ( P < 0.05) and M6G (at both doses) reduced the response to CO 2 at 20 and 40 min after administration, but to a lesser degree than did morphine ( P < 0.05).

Fixed ventilation during tidal volume breathing bronchial challenge may improve repeatability.

Tidal breathing during bronchial challenge shows both between- and within-subject variation. A challenge protocol permitting controlled ventilation was designed in order to improve repeatability of the method. Twenty-five patients were challenged twice with an interval of 2 h. The 2 min ventilation was kept constant at each concentration administered. During the 2 min inhalation of aerosol all expired air (VE) was led through a dry gas meter and respiratory frequency was counted concomitantly. The patients were instructed to achieve the same 2 min ventilation at each dosage. All patients accomplished the two challenges without problems. A PC20 was determined by interpolation on the log dose-response curve. Repeatability was improved compared to what has been found in previous studies on adults, although statistically non-significant when compared to one study. The 95% confidence interval for PC20 based on a single determination was rather narrow, being the observed value +/- 0.58 two-fold concentration differences.

Ventilatory sensitivity to inhaled carbon dioxide around the control point during exercise.

Rapid steady-state CO2 responses were determined in five normal adults at rest and at up to six levels of exercise by injecting pure CO2 at a constant flow into the inspiratory limb of a breathing circuit. Ventilation (V) was measured with a dry gas meter and PCO2 at the mouth was recorded by a mass spectrometer. Mean alveolar PCO2 (PACO2) was taken as equal to end-tidal PCO2 at rest, and during exercise was derived graphically from the sloping alveolar plateaus. The accuracy of the latter method was checked in separate experiments against arterial PCO2 (PaCO2). The mean results showed a linear relationship between change in PACO2 and change in V for work loads ranging from rest to 75 W (r = 0.94-0.98). Above 75 W the response became concave down with an initial essentially isocapnic phase. This suggests that during exercise there is a large increase in CO2 sensitivity about the control point.

Somatostatin inhibits the ventilatory response to hypoxia in humans.

The effects of a 90-min infusion of somatostatin (1 mg/h) on ventilation and the ventilatory responses to hypoxia and hypercapnia were studied in six normal adult males. Minute ventilation (VE) was measured with inductance plethysmography, arterial 02 saturation (SaO2) was measured with ear oximetry, and arterial PCO2 (Paco2) was estimated with a transcutaneous CO2 electrode. The steady-state ventilatory response to hypoxia (delta VE/delta SaO2) was measured in subjects breathing 10.5% O2 in an open circuit while isocapnia was maintained by the addition of CO2. The hypercapnic response (delta VE/delta PaCO2) was measured in subjects breathing first 5% and then 7.5% CO2 (in 52-55% O2). Somatostatin greatly attenuated the hypoxic response (control mean -790 ml x min-1.%SaO2 -1, somatostatin mean -120 ml x min-1.%SaO2 -1; P less than 0.01), caused a small fall in resting ventilation (mean % fall - 11%), but did not affect the hypercapnic response. In three of the subjects progressive ventilatory responses (using rebreathing techniques, dry gas meter, and end-tidal Pco2 analysis) and overall metabolism were measured. Somatostatin caused similar changes (mean fall in hypoxic response -73%; no change in hypercapnic response) and did not alter overall O2 consumption nor CO2 production. These results show an hitherto-unsuspected inhibitory potential of this neuropeptide on the control of breathing; the sparing of the hypercapnic response is suggestive of an action on the carotid body but does not exclude a central effect.

Metabolic correlates in infants and children during anaesthesia and surgery.

In 58 infants and children with body weights between 2.8 and 20.5 kg carbon dioxide production (VCO2 ml min-1) was measured during halothane anaesthesia for minor surgical procedures. In 22 cases measurements were made during both spontaneous and controlled ventilation during the same operation. A non-rebreathing circuit was used. Expired ventilation volume was measured with a dry gas meter and expired gas collected during 3-5 min in a Douglas bag. The carbon dioxide fraction of exhaled gas was determined with a sampling Gould capnograph. A respiratory quotient (RQ) of 0.8 was used to calculate oxygen consumption (VO2 ml min-1). During spontaneous breathing, regression analysis of the relationship between VCO2 and kg and between VO2 and kg showed high intercepts while corresponding relations to kg3/4 revealed an almost direct proportionality. Thus, VCO2 and VO2 ought to be related to body weight in kg3/4 in spontaneously breathing children. The mean value (+/- 1 s.d.) for VCO2 was 11.4 +/- 3.1 ml kg-3/4 and for VO2 14.2 +/- 3.9 ml kg-3/4. During controlled ventilation, the relationship between kg b.w. showed for VCO2 as well as for VO2 an almost direct proportionality with a mean value (+/- 1 s.d.) for VCO2 of 6.3 +/- 1.6 ml min-1 kg-1 and for VO2 of 7.8 +/- 2.0 ml min-1 kg-1. Prediction of VO2 for infants and children of this size could be based upon 14 X kg3/4 during halothane anaesthesia and surgery.

Long-term flow measurement: an assessment of the Siemens Servo 900B expiratory flowmeter.

The accuracy and linearity of three Siemens Servo 900B expiratory flowmeters have been assessed by comparison with a dry gas meter. Their performance was reassessed after 792,966 and 950 h respectively. The effects of changes in respiratory rate, relative humidity and oxygen concentration on the meters were studied. It was found that the meters were accurate and linear and that reliable measurements could still be made after long periods of continuous use. The meters were found to be less accurate at low respiratory rates. Relative humidity had little effect on flow measurement. Changes in oxygen concentration, and hence viscosity, led to errors of up to 16% in flow measurement.

The 'Oxylog': an evaluation.

Abstract The Oxylog is a portable instrument designed to measure the oxygen consumption ([Vdot]02) an ambulatory subject. Steady-state measurements have been made, using an Oxylog, of inspiratory volume ( [Vdot]1) [Vdot]02 during bicycle ergometer exercise at work rates ranging from 30 to 150 W. These measurements have been compared with simultaneous measurements of expiratory volume ([Vdot] E) and [Vdot]O2 made using a dry gas meter and mass spectrometer. Four experiments were conducted, during which a total of 433 comparative measurements were made. In two experiments the Oxylog significantly underestimated [Vdot]O2 (by 4-4 and 5-6%). Averaging over the four experiments, however, the underestimate reduced to 1-5%, which could be accounted for by a respiratory exchange ratio of approximately 0-9. There was, overall, no significant difference between [Vdot] 1 and [Vdot] E. It is concluded that the Oxylog is sufficiently accurate for the reliable determination of [Vdot]02 and of energy expenditure under fi...

Measurement of respiratory gas exchange during artificial respiration.

This paper reports a new system for the continuous measurements of respiratory gas exchange in ventilated subjects. It involves mixing some of the inspired gas with all of the expired gas and withdrawing the mixture at a constant rate through a dry gas meter that measures the flow. The inspired gas and expired gas mixtures are sampled and O2 and CO2 concentrations measured with a paramagnetic gas analyzer and a capnograph, respectively, to an accuracy of 0.01%. Evidence is presented to confirm the necessary stability and sensitivity of these instruments. It is possible to use the system with high inspired O2 concentrations, with ventilators where there is incomplete separation of inspired and expired gas, and in the presence of intermittent mandatory ventilation, positive end-expiratory pressure, and continuous airway pressure. The system was compared with the N2-dilution method and with the collection of expired gas in a Douglas bag in dog experiments and with patients in the intensive therapy unit. Excellent correlation between these methods was found in all circumstances.

A new device for continuous measurement of gas exchange during artificial ventilation.

A new apparatus, which uses a fuel cell for measuring O2 concentration and calculates O2 consumption (VO2), has been developed for use on the Servo Ventilator. Together with an IR CO2 Analyzer, this equipment also provides CO2 production, end-tidal CO2 concentration, and the respiratory quotient.l The accuracy of this equipment was evaluated by comparison with results from two standard methods: the Scholander technique in combination with a dry gas meter, and mass spectrometry combined with a wet gas meter. The results show that the differences between the VO2 calculated from this equipment and two other standard methods are less than 5%. Thus, the accuracy of the new equipment seems reliable enough to make it a valuable tool in clinical use.

The measurement of metabolic gas exchange and minute volume by mass spectrometry alone

Metabolic gas exchange and respired minute volume were measured on 37 occasions in 9 normal adults on exercise and at rest, using the concentration of an injected gas, argon, as a measure of flow. These measurements were compared with simultaneous Douglas bag collections in which volumes were determined with a dry gas meter. The two types of measurements agreed within ±5%. It was concluded that this technique, designed for the remote monitoring of unconscious patients was suitable for a wide variety of clinical and experimental situations.

Errors in the Calibration of EPA Method 5 Dry Gas Meters

The practice of using dry gas meter outlet pressure and average of inlet and outlet temperatures is recommended by both EPA and Environment Canada. Use of the average temperature and outlet pressure introduces errors in the meter calibration. Instead, inlet temperature and pressure should be used to adjust the measured volume. The general principle of using inlet meter conditions has been pointed out by Hendrickson, ''For determining the temperature and pressure conditions of the air flow being measured, sensing devices should be installed in the line near the inlet of the metering unit.'' The ideal situation would be to measure the temperature and pressure within the compartments of the dry gas meter. Since this is not possible, a close approximation of the metering conditions may be assumed by taking temperature and pressure measurement at the meter inlet. The importance of using inlet conditions can best be seen by studying the workings of the dry gas meter.

Nomograph for Field Checking Meter Calibrations on EPA-Type Stack Sampling Trains

In a typical "EPA train" for stack sampling, there are two meters, the dry gas meter and the orifice meter, which require periodic calibration. The controversy which presently exists over the required frequency of calibration is the result of using meters which rarely need calibration, but which have the potential of changing calibration at any time.

The accuracy of a dry gas meter to monitor ventilation during exercise

Several reports (Cunningham, 1969; Henry and Katch, 1972; Mayhew, 1973; Wilmore, 1968; Wilmore and Costill, 1974) have described procedures to measure pulmonary ventilation (Ne) continuously during exercise from a Parkinson-Cowan-CD4 dry gas meter (PC-CD4). Since the accuracy of the calculated oxygen consumption is determined in part by the accuracy of the measured Ve, it is critical that the PC-CD4 readings

Calibration of the high-volume air sampler.

Abstract The use of either a variable voltage transformer (Variac) for regulating the fan speed or resistances has been widely accepted for varying the air flow through a high-volume sampler during calibration. Calibration data for the Staplex high-volume sampler demonstrate that significant differences exist between the calibration results obtained by the two metheds. Calibration curves obtained with a bellows-type dry gas meter and a rotating vane anemometer clearly illustrate that resistances should be used as the standard procedure for varying the flow rate during calibration of the Staplex high-volume sampler. A simplified calibration procedure utilizing a rotating vane anemometer at the sampler inlet is described.

DRY DISPLACEMENT GAS METERS

SUMMARY The development, working, testing and calibration of the dry displacement gas meter is described. Three models in current use in our laboratory have been tested before and after mechanical overhaul. The dry gas meter is cheap, robust, and accurate enough for measuring gas volumes in most applications.