External Venting Research Articles

External venting flame models: Criticality and challenges of application in a large-scale informal settlement fire spread model

Informal settlements can be prone to extensive fire spread, driven to a significant degree by external venting flame (EVF). Development of a successful large-scale urban fire spread model hinges on the applied submodels’ ability to quantify EVF characteristics. The first characteristics to capture are the flame dimensions, however, existing empirical models for this are found to be inaccurate and/or contextually inappropriate for direct application to informal settlement fire spread scenarios. This paper attempts to numerically verify current flame dimension models highlighting where there are discrepancies in the numerical theory that underpin them. New empirical correlations are then created for EVF height and length that, whilst subject to further data input, more robustly capture EVF characteristics seen in experiments.

Experimental study on flame pulsation behavior of external venting facade fire ejected from opening of a compartment

The present study investigated experimentally the flame pulsation magnitude (ratio of maximum flame height to mean flame height; ratio of mean flame height to continuous flame height) and flame pulsation frequency of the external venting facade fire (EVF) ejected from opening of a compartment. Experiments were conducted by employing three model-scale fire compartments with an opening and a vertical facade wall. Fifteen different opening geometries were considered. For the flame pulsation magnitude of EVF, results showed that the ratio of maximum flame height to the mean flame height was about 1.30, while the ratio of mean flame height to continuous flame height was about 1.60; both of them were independent of opening geometries and heat release rates. The flame pulsation frequency of EVF increased with increasing of heat release rate, meanwhile decreased with increasing of opening size (or namely opening characteristic lengths: ℓ1= (AH1/2)2/5; ℓ2= (AH2)1/4). The measured flame pulsation frequency of EVF showed to be much lower than the predicted values by previous classic models developed for free buoyant diffusion flames, which is due to physically the inherent special exit condition (with initial horizontal convection flow of heat) at the opening for EVF. A new formula was proposed for the flame pulsation frequency of EVF in terms of a non-dimensional function between Strouhal number (St) and Froude number (Fr), using Vf∝gZf as the characteristic flame uprising velocity and ℓ1= (AH1/2)2/5 as the characteristic length of the source exit convection flow condition at the opening. The flame pulsation frequency showed to be well represented by the proposed formula. These new observations and the proposed formula provide essential knowledge for the characterization of flame pulsation behavior of external venting facade fire (EVF) ejected through the opening of a compartment.

P3.47: Multimodality Surgical Management of Patients with Global Gut Dysmotility: Techniques and Long-Term Outcome

Introduction: Global gut dysmotility (GGD) is a severely disabling disorder with the potential to develop gut failure with impaired quality of life. With the lack of effective medical therapy and pacing technology, surgical management with different modalities including gut transplantation (GTx) has recently evolved as part of the multidisciplinary treatment approach for this orphan population. Methods: Between August 2012 and January 2019, a total of 172 patients with the diagnosis of GGD were referred to Cleveland Clinic, Center of Gut Rehabilitation and Transplantation (CGRT). TPN dependence was documented in 116 (76%). Of those, 82 (71%) underwent rehabilitative surgery (RS) and/or GTx. The diagnosis was confirmed by exclusion of gastrointestinal mechanical obstruction with radiologic evidence of global dysmotility including capsule endoscopy and sitz marker methodology. Most patients were adult female (88%) with extensive psychiatric history in more than 50% of the cases. Previous management included pharmacologic therapy, gastric pacing, partial colon resection, and external venting. Results: With the intent to treat or as a bridge to GTx, 62 (76%) underwent RS with completion colectomy and ileorectal anastomosis (n=47), pyloroplasty (n=27) and chimney ileostomy (n=40). GTx with liver-free (n=19) and liver-contained (n=1) allograft was performed in a total of 20 (24%). Of these transplant recipients, 7 (35%) failed RS at our institution. With a mean follow up of 32 + 15 months, 160 patients are currently alive with an overall survival rate of (93%). In those with TPN dependency, the survival rate was better after RS (94%) compared to GTx (80%). Restoration of oral tolerance with achievement of full nutritional autonomy was accomplished in 20 (32%) and 10 (63%) of the current survivors, respectively. Conclusion: Gut Rehabilitative surgery and transplantation are effective treatment modalities for GGD patients. RS can be utilized as a long-term therapy or bridge for gut transplantation.

PIN8 - Open Vs. Closed Intravenous Systems: a Systematic Review and Meta Analysis of Published Evidence

There are two types of intravenous (i.v.) fluid containers in use: a collapsible plastic container that requires no external venting for the bag to empty (a closed infusion container) and a non-collapsible container (glass bottle or semi-rigid plastic bottle) that must be vented externally to allow air to enter and the fluid to egress (an open infusion container). The objective of the review was to carry out meta-analytic statistical pooling of key clinical outcomes which define open vs. closed systems. MEDLINE including was systematically searched, pairing relevant keywords to identify English language articles describing outcomes in clinical studies. Direct meta-analysis technique was employed as-per appropriate algorithms (random effects/fixed effects model) with respect to clinical outcomes (dichotomous/continuous). RevMan 5 software was used for statistical analysis. Meta-analysis showed that there is 3.26 times greater risk of central line blood-stream infections (CLABSI) in open compared to closed system and there is 3.43 times greater odds of CLABSI in open compared to closed system. CLABSI rate in open system ranges from 6.4 to 16.1 CLABSI /1000 CL days and CLABSI rate in closed system ranges from 2.2 to 3.5 CLABSI /1000 CL days. Meta Analysis of evidence pertaining to mortality showed that there is 1.23 times greater risk of death in open compared to closed system and there is 1.28 times greater odds of death in open compared to closed system. Mortality proportion in open system ranges from 2.8% to 23.40% while in closed system it ranges from 0.26% to 16.90%. Furthermore, mean (SD) LOS (ICU days) in open system ranges from 4.5 (7.16) to 17.41(0) whereas mean (SD) LOS (ICU days) in closed system ranges from 4.7(6.94) to 7.9 (8.57). Meta-analytic findings indicate that use of open i.v. systems pose discernible threat to patients and significantly contributes to HAI burden.

A Great Time for Makers

LASER CUTTERS First up is laser cutting. Unlike 3D printers, which deposit material one layer at a time (an instance of additive manufacturing), laser cutters use a powerful laser to cut or engrave material (subtractive manufacturing). While laser cutting has been around for some years, your best bet as an independent maker to get access to one was to join a local hackerspace that already had one of these beauties. Not only were these devices heavy and expensive, they required complicated exhaust and ventilation systems. Recently, a successful crowdfunding campaign hatched the Glowforge “3D laser printer”– a laser cutting device targeted for home use by enthusiasts [Figure 1]. The laser isn’t as powerful as some of the larger systems (the basic model comes with a 40W laser while the pro model offers 45W). But this is likely adequate to cut and etch material such as acrylic, wood and leather. What is most exciting is that this is being designed with home use in mind. You still need to deal with fumes – external venting is a default but it also supports a filter attachment that obviates the need for ventilation. With cheap 3D printers, there have been several reported complaints of foul smelling fumes when used in closed spaces (inhaling the odor of plastic burning is likely never a good thing!). Time will tell how well these filtration solutions work in practice.

Trend Towards Lower Rates of Gastrointestinal Bleeding in Patients Transplanted with HeartWare vs. HeartMate-2 for End Stage Heart Failure

Purpose: Left ventricular assist device (LVAD) augment systemic circulation and improves quality of life in patients suffering from end stage heart failure. Until recently, LVAD implantations had been performed with first generation pulsatile devices. Newer generation pumps work by a central rotor containing permanent magnets. The HeartMate-2 (HM-2), a 2nd generation LVAD is FDA approved for bridge to transplant and destination therapy. Their continuous flow mechanism allows reduction in pump size since external venting is no longer required for long-term pulsatile LVADs. Their generation pumps such as HeartWare (HW) have no bearings, longer durability, smaller size, and are easier to implant. They work by a central rotor containing permanent magnets which use a centrifugal pump where the rotors are shaped to accelerate the blood circumferentially and cause it to move toward the outer rim of the pump. For HM-2, several centers have reported rate of GI bleeds ranging from 15% - 40%. The purpose of this retrospective case control study is to compare the odds of GI bleed in patients implanted with HM-2 vs. HW pumps. Methods: Medical records of 98 patients (84 with HM-2 and 14 with HW), ages 28 - 77 at Penn State Hershey Medical Center from July 2006 through November 2011, were selected. GIB was defined as one guiac-positive stool with a subsequent transfusion of at least two units of PRBC. Results: In HM-2 vs. HW patients, GIB occurred in 20 (24%) vs. 1 (7%), respectively. There was no difference in median [IQR] time to onset of bleed for HM-2 vs. HW which were 51.5 [25.5- 347] vs. 49 [49, 49], p=1.0, respectively. In the multivariable logistic regression, age, sex, and extracorporeal membrane oxygenation (ECMO) prior to LVAD placement were not associated with increased incidence of GI bleed. Odd ratio showed a tread towards decreased rate of GI bleed with HW vs HM-2 (OR=0.21. p=0.190). Heart-Mate-2 Parameters Anticoagulation: Warfarin with goal INR of 1.5 - 2.0 with Aspirin 81 mg daily Speed: 9,000-10,000 rotation per minute (RMP) Flow: 3.5 - 6 L/min as appropriate for body surface area Power: 4 - 8 Watts. HeartWare Parameters Anticoagulation: Warfarin with goal INR of 2.0 - 3.0 combined with aspirin 81 mg daily Speed: 2,600 - 3,200 rpm Flow: 3.5 - 6 L/min as appropriate BSA Power: 3 - 6 watts Conclusion: There is an early trend to a decrease rate of GIB with the 3rd generation HeartWare LVAD pumps. This could be explained by the decreased rotations per minute leading to decreased shear stress. HW devices are offered solely to transplant candidates, which could add bias. Further prospective study as numbers of HW implants accrue will be necessary.

응축기의 비응축 가스 배출 타입에 따른 틈 간격 비율의 영향에 대한 수치적 연구

본 논문은 응축기의 비 응축 가스 배출 타입에 따른 틈 간격의 비율이 응축기의 성능에 미치는 영향에 관하여 다공성 매질 개념을 적용한 수치적 연구에 관한 것이다. 다공성 매질의 개념을 이용한 응축기의 성능 해석에서는 응축기기 내부의 다관군을 다공성 매질로 간주하며, 다관군에 의한 압력강하는 상관식으로 반영한다. 상용수치해석 프로그램인 Fluent 와 user-defined functions 를 이용하여 McAllister 응축기에 다공성 매질 개념을 적용하여 3 차원 응축량을 해석하였다. 순수증기의 해석에서는 틈 간격이 응축량에 미치는 영향이 거의 없었다. 그러나 비 응축가스가 포함되어 있으며, 외부 배출의 경우 틈 간격은 응축량에 매우 큰 영향을 미쳤는데, 틈 간격이 줄어듦에 따라 응축량이 매우 증가하는 결과를 얻었다.

Are laptop ventilation-blowers a potential source of nosocomial infections for patients?

Inadequately performed hand hygiene and non-disinfected surfaces are two reasons why the keys and mouse-buttons of laptops could be sources of microbial contamination resulting consequently in indirect transmission of potential pathogens and nosocomial infections. Until now the question has not been addressed whether the ventilation-blowers in laptops are actually responsible for the spreading of nosocomial pathogens. Therefore, an investigational experimental model was developed which was capable of differentiating between the microorganisms originating from the external surfaces of the laptop, and from those being blown out via the ventilation-blower duct. Culture samples were taken at the site of the external exhaust vent and temperature controls were collected through the use of a thermo-camera at the site of the blower exhaust vent as well as from surfaces which were directly exposed to the cooling ventilation air projected by the laptop. Control of 20 laptops yielded no evidence of microbial emission originating from the internal compartment following switching-on of the ventilation blower. Cultures obtained at the site of the blower exhaust vent also showed no evidence of nosocomial potential. High internal temperatures on the inner surfaces of the laptops (up to 73°C) as well as those documented at the site of the blower exhaust vent (up to 56°C) might be responsible for these findings.

Acoustic pulse flow meter

A time-of-flight flow meter that is particularly useful for measuring the flow of gases, such as steam, uses a spark gap periodically energized with an electrical pulse to generate an acoustic pulse. The pulse is detected by upstream and downstream acoustic detectors that may be capacitive transducers having flexible plates wetted on both sides by the fluid so that no external venting is required. The acoustic detectors may be electrically heated to avoid condensation effects. In some cases the interior of the pipe or other conduit is shaped near the source so as to define acoustic beams aimed at the detectors and so as to concentrate the received acoustic energy on the detectors.

Evaluation of chest seal performance in a swine model: Comparison of Asherman vs. Bolin seal

Chest seals are externally applied devices used to treat an open pneumothorax. There is concern that chest seals used for treatment of an open pneumothorax can fail due to coagulation or malfunction of the external vent and poor skin adherence. Chest seal failure may lead to respiratory compromise or the development of a tension pneumothorax. The objective of this project was to compare the efficacy and adhesive capacity of two chest seals: Asherman and Bolin. An open pneumothorax model in the swine (30 kg) was developed to test the performance of Asherman (n=8) and Bolin (n=8) seals based on haemodynamic and ultrasonographic changes following intrathoracic air and blood infusion. Seal adherence measured on a scale from 0 (poor) to 3 (good) was tested on dry skin and skin soiled with blood. After standardised perforation of the chest cavity and aperture blocking, an air infusion of 372 (S.D. 214 ml) was sufficient to reduce mean arterial pressure (MAP) by 20%. Both chest seals prevented a significant fall in MAP after infusion of 1500 ml air into the chest cavity, and had similar adherence scores (2.6 (S.D. 0.8) and 2.8 (S.D. 0.6)) on dry skin. However, on blood soiled skin the Bolin seal had a higher score (2.7 (S.D. 0.6) vs. 0.4 (S.D. 0.7); p<0.01). Ultrasound did not yield interpretable results to differentiate between Asherman and Bolin seals. The Bolin and Asherman chest seals were equivalent in preventing the development of a tension pneumothorax in this open pneumothorax model. However, the Bolin chest seal demonstrated stronger adherence in blood soiled conditions.

The Rationale for the Vented-crown Technique and Its Application in Today's Dental Practice

It would be safe to assume that the integrity of a full coverage restoration is directly related to its marginal fit. Complete, unimpaired seating of a full coverage restoration can be significantly affected by hydraulic pressure from the cement.1–2 Hydraulic pressure, created by seating a restoration, especially a well-fitting one, can result in a final marginal gap that is clinically unacceptable. Incomplete seating due to hydraulic pressure is a greater problem with posterior teeth. The large, flat occlusal surface of this type of preparation creates a large well or platform for cement to pool and prevent seating. Also, preparations with long, parallel walls and a large occlusal surface are even more of a concern. Anterior preparations tend to be more conical in shape and have no or minimal occlusal table. They may be less affected with the problem of hydraulic pressure.3Improving the marginal fit of restorations can help to prevent the problems of open margins, cement washout, recurrent decay, poor gingival health and disrupted occlusion. The seating of a full coverage restoration can be improved significantly by using external venting,1–24–6 a die spacer7–9 and internal venting.310–12 When the literature is consulted, it is consistently found that, when no relief is used, the marginal gap can vary from 200–100 μ, based on the theory of hydraulic pressure.1–610–14 Using a die spacer will reduce the marginal gap to 60 μ.13–14 The best seating, close to 20 μ, was achieved when an external vent with die spacer was used.1–24–6 Different cement types do not seem to play a significant role in the marginal fit if a die spacer and external venting are used.13–15 Marginal design also does not seem to affect marginal fit, if a die spacer and/or vents are used.16 Actually, the better the casting fits at the margin, the more there is need for relief during seating, because hydraulic pressure has the potential to be a greater problem. An oversized, poor fitting casting cannot build-up as much hydraulic pressure.Venting to reduce internal hydraulic pressure may also have additional benefits with porcelain fused-to-metal crowns. Research indicates that internal hydraulic pressure can deform a crown and possibly contribute to premature porcelain fractures.17–18 The escape provided by the vent is a great way to reduce these internal hydraulic pressures and the potential for lateral deformation during seating.The use of a single internal vent channel placed on the wall of a preparation has also been shown to improve the seating of a full coverage restoration.310–12 The escape channel needs to be placed as close as possible to the margin and facilitate the release of excess cement. If the escape channel is under extended, in the range of 2 mm or greater from the margin, the benefit of this technique is lost. This technique has shown results in the 40–50 μ range for marginal gap sizes. It is a simpler technique and does not require a vent hole to be repaired.The goal of obtaining the best marginal fit seems to lie with using the die spacer and an external vent. The ease of using a die spacer alone will provide consistent margins of 60 μ, which may very well be clinically acceptable. However, when the extra step is taken with an external vent, the following benefits are achieved:This article reviews a simplified external venting technique first described by Basset2 and later by Seberg.22 This technique will be extrapolated to porcelain fused-to-metal crowns. The technique demonstrates a simple, yet effective, way to seal the external vent hole. Once the vent hole is sealed with a gold pin and polished, it is practically invisible. An example will also be shown and briefly discussed with a case using an internal vent.Special thanks go to my lab support: Penny Marazzo, Stoneybrook Noble Gold, 242 Stoneybrook Rd, Newtown, PA 18990, USA, (215) 860–3936 and Art Nelson, Bjorn Dental Lab, 16 Polly Drummond Hill Rd, Suite 7, Newark, DE 19711, USA, (302) 454-8245.

Loudspeaker having a dual chamber acoustical enclosure with two external vents and one internal vent

A loudspeaker that includes an acoustical enclosure that has an internal wall that divides the enclosure into first and second subchambers, an electro-acoustical transducer having a vibratable speaker cone mounted in an opening provided in the internal wall of the acoustical enclosure, an internal vent provided in the internal wall of the acoustical enclosure for pneumatically coupling the first and second subchambers, a first external vent provided in a wall of the first subchamber for pneumatically coupling the first subchamber to an exterior environment outside of the acoustical enclosure, and a second external vent provided in a wall of the second subchamber for pneumatically coupling the second subchamber to the exterior environment. In one embodiment, a ratio of the acoustic mass of the internal vent to the acoustic mass of the second external vent is in a range of approximately 3/1 to 7/1. In another embodiment, a ratio of the acoustic mass of the first external vent to the acoustic mass of the second external vent is in a range of approximately 15/1 to 30/1. In both embodiments, a ratio of the volume of the first subchamber to the volume of the second subchamber is in a range of approximately 0.3 to 2.5. In both embodiments, at least one of the internal and/or external vents can be substituted with a passive radiating element such as a drone cone.

Experimental investigations on the external pressure during venting

Abstract Experiments of explosion venting in different conditions were performed in a cylindrical vessel with a vent duct; the pressure-time profiles from four transducers mounted in the line-of-sight centerline outside the vessel and the clear sequential shadowgraphs of external venting flow field taken by a high-speed shadowgraph imaging system were obtained. Based on these results, the characteristics of the external pressure field during venting were discussed systematically to explain the generation mechanism of the secondary explosion. In addition, the variations of the intensity of the secondary explosion in different venting conditions, namely the failure pressure, ignition location, area blockage ratio or equivalence ratio of the fuel, were also analyzed in detail.

Toxic product yields and hazard assessment for fully enclosed design fires

Fires in multi-compartment buildings often occur in enclosed spaces or in enclosures opening into other rooms or corridors. Where such fires occur in relatively small enclosures, with limited external venting, the growth of the fire itself remains restricted. If large vents are present opening into large enclosed spaces or to the outside, flashover may occur. In either case these fires are likely to become oxygen vitiated, producing large amounts of smoke and toxic products. Fire-retarded (FR) and non-FR materials behave differently in these situations from the well-ventilated conditions in most standard tests, with smaller differences in toxic product yields. The main hazard to building occupants is the rapid contamination of building spaces by toxic smoke. Visual obscuration and irritancy of smoke impedes escape efficiency, affecting escape behaviour and slowing travel speeds. This may be followed by incapacitation, primarily due to exposure to asphyxiant gases (mainly CO and HCN), and death. A series of full-scale fire tests conducted in enclosed test rigs and buildings is reported, in which detailed measurements of smoke, heat, toxic gases and time to detection were made, enabling assessment of time to incapacitation using Fractional Effective Dose methodology. Also described are hazard analyses for fires in which an active suppression was used. These include fires in two-storey maisonettes with and without domestic sprinklers. Results are presented on the relationship between plume oxygen and CO concentrations, and between CO and HCN yields. The effects of interactions between fuel type and load, ventilation and building enclosures are discussed and their implications for choice of design fires appropriate to different fire scenarios. © 2000 Society of Chemical Industry

Toxic product yields and hazard assessment for fully enclosed design fires

Fires in multi-compartment buildings often occur in enclosed spaces or in enclosures opening into other rooms or corridors. Where such fires occur in relatively small enclosures, with limited external venting, the growth of the fire itself remains restricted. If large vents are present opening into large enclosed spaces or to the outside, flashover may occur. In either case these fires are likely to become oxygen vitiated, producing large amounts of smoke and toxic products. Fire-retarded (FR) and non-FR materials behave differently in these situations from the well-ventilated conditions in most standard tests, with smaller differences in toxic product yields. The main hazard to building occupants is the rapid contamination of building spaces by toxic smoke. Visual obscuration and irritancy of smoke impedes escape efficiency, affecting escape behaviour and slowing travel speeds. This may be followed by incapacitation, primarily due to exposure to asphyxiant gases (mainly CO and HCN), and death. A series of full-scale fire tests conducted in enclosed test rigs and buildings is reported, in which detailed measurements of smoke, heat, toxic gases and time to detection were made, enabling assessment of time to incapacitation using Fractional Effective Dose methodology. Also described are hazard analyses for fires in which an active suppression was used. These include fires in two-storey maisonettes with and without domestic sprinklers. Results are presented on the relationship between plume oxygen and CO concentrations, and between CO and HCN yields. The effects of interactions between fuel type and load, ventilation and building enclosures are discussed and their implications for choice of design fires appropriate to different fire scenarios. © 2000 Society of Chemical Industry

Closed Loop Control of Atmospheres for Soldering

Well designed stable reflow ovens and wave machines can be operated at low rates of the inerting gas. One problem is that at the lowest flow rate settings changes in room draughts and in external venting conditions can affect the internal oxygen levels unless the flow rates are altered. The internal oxygen levels can drift or suddenly alter. This generally means that the ovens are operated at higher flows than necessary in order to ensure steady operations below some desired oxygen level without excessive operator intervention. A closed‐loop control system using the output of internal oxygen meters to vary the flow rates set by mass flow meters is one way to ensure steady operation. One such system — NITRAPILOT™ control system—has been developed by BOC Gases as a stand alone system that can be added to existing equipment. The results of small‐scale and production level testing on this system are described in the present paper. Reduced flow rates can be achieved for stable set point oxygen levels at critical locations. An equally significant benefit, particularly when used in conjunction with data logging, is that the system assists in statistical process control since it ensures, monitors and logs compliance with process recipes without operator intervention.

Cora valveless pulsatile rotary pump: New design and control

For decades, research for developing a totally implantable artificial ventricle has been carried on. For 4 to 5 years, two devices have been investigated clinically. For many years, we have studied a rotary (but not centrifugal) pump that furnishes pulsatile flow without a valve and does not need external venting or a compliance chamber. It is a hypocycloidal pump based on the principle of the Maillard-Wankel rotary compressor. Currently made of titanium, it is activated by an electrical brushless direct-current motor. The motor-pump unit is totally sealed and implantable, without noise or vibration. This pump was implanted as a left ventricular assist device in calves. The midterm experiments showed good hemodynamic function. The hemolysis was low, but serious problems were encountered: blood components collecting on the gear mechanism inside the rotor jammed the pump. We therefore redesigned the pump to seal the gear mechanism. We used a double system to seal the open end of the rotor cavity with components polished to superfine optical quality. In addition, we developed a control system based on the study of the predicted shape of the motor current. The new design is now underway. We hope to start chronic experiments again in a few months. If the problem of sealing the bearing could be solved, the Cora ventricle could be used as permanent totally implantable left ventricular assist device.

Well for use in heart-lung or regional perfusion systems.

We have had a stainless steel well constructed * for use in extracorporeal circulation systems. This apparatus facilitates: (1) measurement of perfusion pressure; (2) addition of materials to the system; (3) withdrawal of samples for analysis; (4) monitoring of the temperature of the perfused blood; (5) removal of trapped air by external venting. Description The chamber is constructed of highly polished stainless steel (Figs. 1 and 2). It is 4.7 cm. in depth and has an inner diameter of 2.1 cm. and a capacity of 16 cu. cm. The cap is screwed into the main chamber over a rubber gasket. Into the top of the cap is welded a ridged stainless steel nipple which is adapted to plastic tubing (Mayon) of 1/4 in. internal diameter. In the perfusion system, this nipple is connected by a 25 cm. length of tubing, loosely plugged above with sterile cotton to a Tycos manometer. Air