Decompression Failure Research Articles

The Theory of Decompression Failure in Polymers During the High-Pressure Processing of Food

The occurrence of blistering and the formation of bubbles in matrices after a sudden pressure drop is a well-known phenomenon in many fields, including in the petroleum industry (“explosive decompression failure”), in diving (decompression sickness), in the infrastructure of hydrogen fuel cells, in the foaming of polymers, and in the high-pressure processing of food. This usually undesirable effect is caused by the increased absorption of gas in the polymer under high-pressure conditions and the subsequent supersaturation and increase in free energy on rapid pressure release. The exact mechanisms of the resulting expansion of gas, and hence the formation of bubbles, are not fully understood. Regarding the high-pressure processing of food where pressures of up to 6000 bar are reached at moderate temperatures, little information is available about the key factors involved in decompression failure. This review summarizes results and findings from relevant research areas to understand polymer decompression failure. The first part of this review describes the transport properties of gases in polymers under high pressure (sorption and desorption, diffusion coefficient, and permeability coefficient). The second part focuses on damage mechanisms and discusses parameters such as material properties, the nature of the gas, and process conditions (e.g., temperature, decompression rate). Knowledge gaps and proposed research are highlighted.

The Relationship Between Optic Nerve Sheath Decompression Failure and Intracranial Pressure in Idiopathic Intracranial Hypertension.

To our knowledge, there are no studies of patients with idiopathic intracranial hypertension (IIH) that address the relationship between level of intracranial pressure (ICP) and likelihood of progressive visual loss despite uncomplicated optic nerve sheath decompression (ONSD). This study investigated whether patients with IIH undergoing ONSD had a higher risk of surgical failure if opening pressure (OP) on lumbar puncture was ≥50 cm H2O compared to those with OP <50 cm H2O. We conducted a retrospective chart review of consecutive patients with IIH who failed maximal medical therapy and underwent ONSD between January, 1992 and November, 2014, and were followed at least 3 months postoperatively. The main outcome measure was the relationship between OP on lumbar puncture and ONSD failure. We also investigated the relationship of OP with visual acuity, visual fields, age, and gender. During this period, 174 patients met inclusion criteria. Of the 40 patients who had an OP ≥50 cm H2O, 6 (15%) had progressive visual loss after uncomplicated ONSD, vs 6 (4.5%) of 134 patients with an OP <50 cm H2O (P = 0.032, Fisher exact test). Patients with worse visual acuity at presentation also had a higher risk of progressive visual loss after ONSD (P < 0.001, Cochran-Armitage trend test), as did men (P = 0.048, Fisher exact test). Patients with IIH and an OP ≥50 cm H2O had a 3-fold increased risk of failure of ONSD to prevent progressive visual loss, requiring a shunting procedure when compared to those with OP <50 cm H2O. Visual acuity at presentation and male sex also were associated with progressive visual decline after ONSD. These risk factors merit closer follow-up in the postoperative period when signs of further visual deterioration would indicate an urgent need for neurosurgical shunting.

Needle decompression of tension pneumothorax: Population-based epidemiologic approach to adequate needle length in healthy volunteers in Northeast Germany.

Tension pneumothorax is one of the leading causes of preventable death in both military and civilian trauma patients. Needle decompression is recommended in trauma guidelines as an emergency procedure to relieve increased intrapleural pressure. The main reason for decompression failure is reported to be insufficient needle length in proportion to the chest wall thickness (CWT). So far, population-based epidemiologic data on CWT are missing. Therefore, it was the aim of this work to investigate the CWT in the second intercostal space, midclavicular line, based on magnetic resonance imaging data of a large population-based sample. The second aim of this study was to explore the potential risk of iatrogenic lesions caused by the proximity of the intended puncture track to the internal mammary artery. A total of 2,574 healthy volunteers (mean [SD] age, 53.3 [13.9] years; range, 21-89 years) from the population-based cohort Study of Health in Pomerania (SHIP) were enrolled. CWT and the distance from the intended puncture track to the internal mammary artery were investigated with the chest sequences of a standardized 1.5-T whole-body magnetic resonance imaging. For all 5,148 measured sites in 2,574 volunteers, the mean (SD) CWT was 5.1 (1.4) cm. The mean body mass index was determined to be 27.7 kg/m. The CWT correlated significantly with body weight and body mass index. The internal mammary artery was located medial to the intended puncture site in all participants; the mean (SD) distance was 5.7 (0.7) cm on the right and 5.5 (0.7) cm on the left side. Based on the population-based epidemiologic data presented in this study, the use of a needle of 7 cm in length is recommended to decompress a tension pneumothorax in the second intercostal space in the midclavicular line, which might successfully decompress more than 90% of the participants in this study. When using this anterior approach at the anatomically correct puncture site, safety margin to the internal mammary artery is sufficient so that the risk of iatrogenic lesion of the internal mammary artery should be minimal. Therapeutic/care management study, level IV.

Rapid Gas Decompression Performance of elastomers – A study of influencing testing parameters

Materials used for the oil and gas industry are exposed to high pressure, high temperature and several aggressive fluids and gases. Concerning the still rising oil and gas product demand the development of new oil and gas valves is indispensable. Therefore, new reliable materials to guarantee facility safety at extreme operating conditions are needed. The presented study deals with a specific failure, the rapid gas decompression failure, which occurs due to the exposure to such extreme conditions. This failure leads to crack initiation, crack growth and in the worst case to the complete fragmentation of the component. For the characterization of this failure a hydrogenated acrylonitrile butadiene based rubber with an acrylonitrile content of 36% was exposed to several temperatures, saturation pressures, gas mixtures and different depressurization rates. Whereas, the rising testing temperature leads to decreasing volume change during the depressurization, the increase in saturation pressure, a higher decompression rate and a higher amount of carbon dioxide clearly lead to an increasing of the maximum observed volume change. Based on the observed volume change and the material ranking, determined using common testing standards NACE International (2003) and NORSOK (2001) a correlation to polymer physical principals was established.

Chest wall thickness and decompression failure: A systematic review and meta-analysis comparing anatomic locations in needle thoracostomy

IntroductionCurrent Advanced Trauma Life Support guidelines recommend decompression for thoracic tension physiology using a 5-cm angiocatheter at the second intercostal space (ICS) on the midclavicular line (MCL). High failure rates occur. Through systematic review and meta-analysis, we aimed to determine the chest wall thickness (CWT) of the 2nd ICS-MCL, the 4th/5th ICS at the anterior axillary line (AAL), the 4th/5th ICS mid axillary line (MAL) and needle thoracostomy failure rates using the currently recommended 5-cm angiocatheter. MethodsA comprehensive search of several databases from their inception to July 24, 2014 was conducted. The search was limited to the English language, and all study populations were included. Studies were appraised by two independent reviewers according to a priori defined PRISMA inclusion and exclusion criteria. Continuous outcomes (CWT) were evaluated using weighted mean difference and binary outcomes (failure with 5-cm needle) were assessed using incidence rate. Outcomes were pooled using the random-effects model. ResultsThe search resulted in 34,652 studies of which 15 were included for CWT analysis, 13 for NT effectiveness. Mean CWT was 42.79mm (95% CI, 38.78–46.81) at 2nd ICS-MCL, 39.85mm (95% CI, 28.70–51.00) at MAL, and 34.33mm (95% CI, 28.20–40.47) at AAL (P=.08). Mean failure rate was 38% (95% CI, 24–54) at 2nd ICS-MCL, 31% (95% CI, 10–64) at MAL, and 13% (95% CI, 8–22) at AAL (P=.01). ConclusionEvidence from observational studies suggests that the 4th/5th ICS-AAL has the lowest predicted failure rate of needle decompression in multiple populations. Level of evidenceLevel 3 SR/MA with up to two negative criteria. Study typeTherapeutic.

Diffuso-Kinetics and Diffuso-Mechanics of Carbon Dioxide / Polyvinylidene Fluoride System under Explosive Gas Decompression: Identification of Key Diffuso-Elastic Couplings by Numerical and Experimental Confrontation

The work aims at identifying the key diffuso-elastic couplings which characterize a numerical tool developed to simulate the irreversible ‘Explosive Decompression Failure’ (XDF) in semi-crystalline polymer. The model proposes to predict the evolution of the gas concentration and of the stress field in the polymer during the gas desorption [DOI: 10.1016/j.compositesa.2005.05.021]. Main difficulty is to couple thermal, mechanical and diffusive effects that occur simultaneously during the gas desorption. The couplings are splitting into two families: indirect coupling (i.e., phenomenology) that is state variables (gas concentration, temperature, and pressure) dependent. direct coupling, (i.e., diffuso-elastic coupling) as polymer volume changes because of gas diffusion; The numerical prediction of the diffusion kinetics and of the volume strain (swelling) of PVF2 (polyvinylidene fluoride) under CO2 (carbon dioxide) environment is concerned. The prediction is carried out by studying selected combinations of couplings for a broad range of CO2 pressures. The modeling relevance is evaluated by a comparison with experimental transport parameters analytically identify from solubility tests.A pertinent result of the present study is to have demonstrated the non-uniqueness of the coefficients of diffusion (D) and solubility (Sg ) between the diffuso-elastic coupling (direct coupling) and indirect coupling. Main conclusion is that it is necessary to consider concomitantly the two types of couplings, the indirect and the direct couplings.

Influence of carbon black on decompression failure and hydrogen permeation properties of filled ethylene‐propylene–diene–methylene rubbers exposed to high‐pressure hydrogen gas

AbstractEight carbon black (CB)‐filled ethylene–propylene–diene–methylene linkage (EPDM) rubbers were manufactured by varying the content and type of CB. Then, the relationship among crack damage caused by high‐pressure hydrogen decompression, the hydrogen permeation properties, and the mechanical properties of the rubbers was investigated. The hydrogen gas permeability of the rubbers decreased with an increase in the CB content and depended little on primary particle size. In contrast, the hydrogen gas diffusivity and solubility depended on both the CB content and primary particle size, that is, the hydrogen gas diffusivity decreased with an increase in the CB content and a decrease in the primary particle size, and the hydrogen gas solubility increased with an increase in the CB content and a decrease in the primary particle size. As for the mechanical properties, the CB‐filled rubbers were more strongly reinforced by an increase in the CB content and a decrease in the primary particle size. The crack damage by high‐pressure hydrogen decompression became larger as the ratio of the hydrogen gas solubility to estimated internal pressure at crack initiation relating to the mechanical properties became larger. As a smaller CB particle increases the hydrogen gas solubility of EPDM rubbers, while at the same time it reinforces the rubbers, the crack damage in the CB‐filled rubbers was not influenced by the primary particle size. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Evaluation on High-Pressure Hydrogen Decompression Failure of Rubber O-ring Using Design of Experiments

The rubber O-rings used in high-pressure hydrogen environment sometimes suffer from the decrease in durability due to decompression failure. A high-pressure durability tester, which enables rubber O-rings to expose repeatedly high-pressure hydrogen gas at arbitrary test conditions, was employed, and then sensitive factors for the durability of the O-rings were evaluated by using a L18 orthogonal array. Of lower-limit pressure, upper-limit pressure, material, temperature, O-ring filling ratio, holding time at lower limit, holding time at upper limit, and decompression time, it was clarified that the material, temperature, O-ring filling ratio, and decompression time were sensitive factors.

Characterization of the fracture behavior of NBR and FKM grade elastomers for oilfield applications

The monotonic fracture behaviour of two elastomer compounds (HNBR and FKM) was characterized in this study. These elastomeric materials are frequently used in many oilfield applications (e.g., seals and hoses) and are exposed to a complex combination of mechanical, thermal and environmental loads. Furthermore, rapid gas decompression failure of these elastomeric materials was observed under real service conditions. A phenomenon termed rapid gas decompression (RGD) damage occurs when elastomer seals exposed to high gas pressure fail in a brittle manner upon the sudden release of the gas pressure. Hence, to support both material development and design efforts, it is of prime theoretical and practical importance to characterize the fracture behaviour of these materials. Fracture mechanics tests using a faint waist pure shear specimen (FWPS) configuration were performed over a wide loading rate range. First, global force and displacement values were measured and single parameter fracture mechanics values in terms of peak tearing energy, T p values were calculated. Furthermore, the crack growth process and the local crack tip deformation were characterized by non-contact optical devices. The digital image correlation technique used allows for the determination of displacement and full-field strain up to a high strain and crack growth rate. Based on above measurements, crack growth resistance curves in terms of tearing energy ( T − Δ c) and crack tip opening angle ( CTOA − Δ c) functions were derived. While a continuous crack growth was observed for HNBR at all loading rates, a discontinuous crack extension was observed for FKM. Finally a phenomenological model was deduced for describing the rapid monotonic crack extension process for these elastomeric compounds.

모바일 와이맥스 환경에서의 효율적인 무선링크 자원 활용을 위한 ROHC Optimistic 모드의 개선 방안

모바일 와이맥스에서 IP 기반의 무선 광대역 서비스를 효율적으로 제공하기 위해, 제한적인 무선링크의 대역폭을 보다 효율적으로 활용하는 방안이 필요하다. 모바일 와이맥스 표준에서 정의된 헤더 압축 기법인 PHS(Payload Header Suppression) 대신에 ROHC(RObust Header Compression) O(Bi-directional Optimistic) 모드를 사용할 경우, 압축효율성과 견고성 면에서 성능을 향상시킬 수 있으나[1, 2], 모바일 와이맥스의 음영서비스 지역이나 비트 에러로 인한 수신단에서의 연속적인 패킷의 손실이 발생할 경우 컴프레서와 디컴프레서가 유지하는 압축 정보가 비동기화되어 O 모드의 패킷 복구 실패율이 증가하게 되므로 이를 보완할 방안이 필요하다. 이에 본 논문에서는, 모바일 와이맥스 환경에서 패킷 손실에 대한 ROHC O 모드의 성능 향상을 위해 O 모드의 압축률과 견고성에 모두 영향을 미치는 Optimistic 파라미터의 값을 동적으로 조절하는 방안을 제안하고, OPNET 시뮬레이터를 사용하여 제안한 방안의 성능 분석을 하였다. In order to efficiently provide IP based Wireless Broadband services in Mobile WiMAX, schemes for more efficiently utilizing a limited bandwidth in radio links are needed. Robust Header Compression (ROHC), a standard header compression scheme proposed by IETF, Bi-directional Optimistic (O) mode provides higher compression efficiency and robustness compared with Payload Header Suppression (PHS) which is an optional header compression scheme for mobile WiMAX [1, 2]. However, if consecutive packet losses occur because of a Shadow Region of Mobile WiMAX or bit errors, header decompression failure rate of the ROHC O mode increases due to inconsistency of the compression information between the Compressor and the Decompressor. Therefore, a complementary mechanism is needed. In this paper, we propose an approach for the dynamic adjustment of an optimistic parameter, which has an effect on both the compression efficiency and the robustness, for improving the performance of ROHC O mode. We also analyze the performance of the proposed approach using an OPNET simulator.

Predictive factors for surgical indication in adhesive small bowel obstruction

Background Small bowel obstruction (SBO) after abdominal surgery is usually treated successfully with intestinal decompression using a long nasointestinal tube (LT), but some cases fail to respond. Methods Clinical background and laboratory data on admission were evaluated retrospectively for 53 patients with adhesive SBO to determine predictive factors for failure of LT decompression, and the appropriate timing of laparotomy was investigated. Results Complete SBO (no evidence of air within the large bowel) and increased serum creatine phosphokinase (≥130 IU/L) were independent predictive factors for LT decompression failure. Laparotomy was indicated in 14 patients (9 and 5 with complete and partial SBO, respectively), whereas successful LT decompression occurred in 39 patients (9 and 30, respectively). Resolution of SBO took significantly longer for complete SBO (6.3 days) than for partial SBO (2.6 days). Conclusions Patients with complete SBO or high serum creatine phosphokinase (CPK) may not respond to LT decompression. Laparotomy is appropriate after non-response for 7 and 3 days for complete and partial SBO, respectively.

Gas induced damage in poly(vinylidene fluoride) exposed to decompression

This paper will discuss the nature of the gas induced damage in a poly(vinylidene fluoride) (PVDF) exposed to `explosive' or rapid pneumatic decompression in a carbon dioxide environment. Generally, under high pressure, the polymer absorbs significant amounts of gas. The large quantity of gas absorbed may induce a dilatation of the specimen and also influence the mechanical properties of the polymer. When the ambient pressure is reduced, the polymer will often suffer irreversible mechanical damage; this process is usually termed explosure decompression failure or `XDF'. This paper is presented in four parts. The first part will describe the variation of the mass of the PVDF polymeric sample in a carbon dioxide medium during the compression and the decompression process at 80°C in the pressure range of 0.1–30 MPa. It is shown that the mass of the specimen increases as the pressure increases but, upon decompression under the conditions described, it is quite constant until 15 MPa and then it falls rapidly. The second part describes the corresponding volumetric change of the polymer, in situ, during the compression and the decompression at 80°C. The decompression curve exhibits a dilatation peak centred at around 14 MPa. The decrease of the mass and the size of the sample is related to the generation of cracks in the polymer matrix during decompression. The third part will describe the results of a mechanical deformation experiment on samples exposed to compression–decompression cycles which is used to establish a relationship between the loss of mechanical properties of the sample and the loss of internal coherence due to the presence of internal cracks. A final part summarises the major conclusions which indicate conclusively that the polymer is irreversibly damaged in the decompression process adopted in the current study.

“Explosive Decompression Failure” of Rubbers: A Review of the Origins of Pneumatic Stress Induced Rupture in Elastomers

Abstract The Review first describes the general features of gas induced rupture in elastomers, induced by a reduction in the ambient gas pressure, and introduces the main variables such as the gas-polymer transport and equilibrium properties. The phenomenologieal nature of the failure processes are also described and the characteristics of the failures encountered are summarized. It is proposed that the failure processes, which involve bubble expansion and subsequent tearing of the interior and exterior of the elastomer, arise from the action of at least two stress fields; one is provided by a simple triaxial tension and the other by an evolving gas concentration gradient. Various routes to model this process are described in the Review. In addition, the importance of the main system variables, on these rupture processes, is assessed and means of deducing, and directly measuring the parameters which may influence the rupture process are described. These include various equilibrium and transient properties such as the extent of the gas mass sorption, the associated volume change and the variation of the mechanical and thermal properties of the polymer-gas system at elevated pressures.

Gas-induced damage in elastomeric composites

Gases may induce extensive and irreversible damage in elastomers when they are allowed to escape from the polymeric matrix. The damage is most evident as internal lacerations and also as an overall change in certain mechanical properties. The damage process, commonly termed explosive decompression failure, is really confined to gas-polymer systems which are initially equilibrated at high pneumatic stresses; greater than 107 Pa. Two interrelated facets of this phenomenon are described in the context of elastomeric composites with particular emphasis on the role of interfacial quality. The results of an optical examination of the internal cracks found during a typical gas-induced rupture cycle are described. The system is a commercial silicone elastomer-glass filler composite where the fillers have been surface modified in order to alter the adhesive strength of the interface. The data indicate that the filler particles significantly modify the stress fields in the elastomer during gas-induced rupture. Essentially, the fillers suppress the development of the characteristic large scale axially symmetrical stress fields in the composites. This visual assessment of the damage is then related to the deterioration in certain mechanical properties of this current system.

Explosive Decompression Resistance of Centrifugal Compressor O-Ring Seals: A Comparative Test Summary and Procedure

Explosive decompression is a phenomenon that can destroy O-ring sealing elements in high-pressure (&gt;3.4 MPa) natural gas compressors during rapid venting to atmospheric pressure. A test rig and procedure have been developed to identify important parameters influencing O-ring seal explosive decompression failure, consistent with utilization of these seals in high-pressure centrifugal compressors. The test rig and procedure are described and comparative test results presented.

Vestibular nerve section and saccus decompression: an evaluation of long-term results.

The 1972 AAOO committee (Alford, 1972) guidelines brought some uniformity into the evaluation of therapy for Menière's Disease. We have adhered to its recommendations in this long-term follow-up report of 21 saccus decompressions and 29 vestibular nerve sections performed on 46 patients between 1968 and 1977. Comparisons between these and other groups have been possible with regard to: control of vertigo; hearing; tinnitus; and development of hydrops in the contralateral ear. All the vestibular nerve section group have enjoyed sustained relief from vertigo. Class D results (recurrent vertigo) account for 14 per cent of the saccus decompression group at one year and 29 per cent at eight to 10-year follow-up. Hearing levels in both groups deteriorated in parallel as time progressed but tinnitus became less noticeable. Nineteen per cent of the long-term review patients showed evidence of developing cochlear hydrops in the contralateral ear. Conservative surgical procedures should be employed whilst any useful hearing exists, though the emphasis remains on controlling vertigo. Saccus decompression, despite its controversial therapeutic basis, will remain the first-line surgical procedure for many otologists. However, in the fit young Menière's cripple or saccus decompression failure with serviceable hearing, vestibular nerve section remains the treatment of choice.