Frequently Asked Questions

• "Actual cc/m" or "accm" is the volumetric flow measured at working conditions (at test pressure.) The actual volume of the gas is compressed by the ratio of the absolute test pressure verses standard pressure (14.696 psia). When stating flow using this terminology, it is imperative that the test pressure and temperature be stated with the flow value. In other words, a 5 accm flow varies with every different pressure and temperature when comparing it to standard conditions.
• "Std cc/m" or "sccm" is the volumetric flow of gas corrected to standard atmospheric conditions (14.696 psia, 293 K (20 C)). Volumetric flow with this designator "std" is always adjusted to the standard pressure and temperature conditions above. Therefore, a 5 sccm leak rate is the same flow at any pressure.
• “ CC/M”代表每分钟立方厘米。它不参考标准或实际条件，因此它是任何一个的缩写。从历史上看，泄漏测试行业以及大多数其他行业都普遍接受了标准条件方面的流动，因为它消除了规定压力和温度的需求。由于大多数人都指“ SCCM”中的泄漏率，因此他们通常将其缩写为“ CCM”。今天，有些人使用“ CCM”来指代“ ACCM”。因此，在标准条件下或在规定的压力和温度下阐明该流量的定义非常重要。

The relationship between "actual cc/m" and "std cc/m is calculated as follows:

LRsccm = {(150 psig +14.7 psia)/14.7 psia} x LRaccm LRsccm = 11.2 x LRaccm

lraccm = {14.7/（150 psig + 14.7 psia）} x lrsccm lraccm = 0.089 lrsccm

• The industry recognized unit of measurement for “gas leakage rate” per the Handbook for Nondestructive Testing, Second Edition, Volume One Leak Testing is flow at standard conditions (14.696 psia, 293 K). This means that scc/m, Pa m3/s, or mbar l/s are the internationally recognized leak rate units.
• 使用“实际CC/M”，某些人可以将“ CC/M”表示为“ CC/M”，需要对测量的压力和温度进行预选赛。
• Download application bulletin, AB141 Leak Rate Units

• There are several manufacturing methods to produce a hole. The important criteria is a long smooth entry, through hole and exit path. This will create repeatable, laminar flow through the hole. The method for manufacturing the hole greatly affects the cost.
  
• 由于这15个微米泄漏标准用于校准泄漏测试系统，因此泄漏标准的流量结果（泄漏速率经过压力）是最重要的特征。辛辛那提测试系统的校准泄漏标准与气缸孔样式等效通道泄漏标准的流动特性相匹配。
  
• Cincinnati Test Systems has produced calibrated leak standards for the leak test market for over 18 years. These leak standards cover a wide range of leak rates and pressures and are available in a wide variety of compact mounting assemblies.
  
• Our A2LA certified calibration lab has perfected the manufacturing and calibration process to cost effectively produce leak standards to a very consistent specification (+/-1%) of specified leak rate value. Leak standards have a standard price of $475 that includes the calibrated standard, mounting assembly, and calibration certificate.
  
• Re-certification is available for $275 that includes free replacement of the leak standard if it does not flow within the allowable tolerance range.
  
• Download application bulletin, AB142 Equivalent Leak Standards, and specification sheet, Calibrated Leak/Flow Standards .

• The “Quik Test” function is a standard feature in the Sentinel C-20 and Sentinel M24 instruments.
• “Quik Test” evaluates the pressure decay curve within the test cycle and compares it to the original calibration curve. If it is within a specified +/-band of the original calibration curve at a defined time into the test cycle, the instrument will decide whether to accept, reject, or continue the test cycle.
• Since most production parts will test consistently close to the same near-zero leak rate, these parts will be quickly accepted. Since most reject parts are major leakers, they will be quickly rejected. Only the few parts that test as marginal accept or marginal reject will actually use the full test cycle time.
• Complete tests are performed on the marginal parts. Therefore, a quality test is performed on the critical parts that have leak rates close to the reject value. The obvious accept and obvious reject parts are quickly passed or failed.
• Download AB122 C-20 Quik Test.

• “Auto Cal” is a standard feature in the CTS products. It establishes the “No-leak” value and volume of the test part.
• 对于压力衰减仪器，两种自动顺序测试教仪器如何进行“无孔”零件测试，并确定零件的泄漏率关系（基于数量和测试时间）的压力损失。
• 通过测试主良好的部分，仪器可以检测到由于绝热温度效应，测试量的扩展或虚拟泄漏而导致测试期间发生的质量流量或压力损失。
• 对于质量流量仪器，当将恒定压力源（调节器）用作流量计的参考压力时，无需第二次测试。如果将恒定压力体积用作参考压力，则需要进行第二次测试，以确定零件体积与包括恒压体积的总系统体积的比率。当使用恒定压力体积（在测试过程中未进行活跃调节器）时，测得的流量是零件实际泄漏率的一部分。
  
  FLOWorifice = (FLOWmeas – FLOWno-leak) x (Total system volume/constant pressure volume)
  
• Download application bulletin, AB121 Automatic calibration procedure (AUTOCAL) and Process Drift Correction (Zero shift).

• “Process Drift” will minimize the need to re-calibrate the instrument several times a day. It will maintain the accuracy of the test and eliminate the acceptance of marginally bad products in a plant environment with cyclical changes in the environment of the test.
• Pressure decay and mass flow instruments measure changes in flow or pressure loss caused by leaks relative to the flow or pressure loss reading of a non-leaking part determined in AUTO CAL. Because these test methods are affected by the variables of the Ideal Gas Law (PV=nRT), temperature changes, volume changes, and virtual leaks influence the measurements.
• In the manufacturing environment there will be changes in temperature, part volume, and/or virtual leak characteristics. These changes will cause the baseline (no-leak parameter) of the calibration to be inaccurate. (The flow or pressure loss value associated with no-leak will not be correct.)
• The “Process Drift” function monitors the test results and automatically calculates corrections for the calibration data to adjust the flow or pressure loss value associated with no-leak to track the production no-leak results.
• Download application bulletin, AB121 Automatic calibration procedure (AUTOCAL) and Process Drift Correction (Zero shift).

• You can mount a normally closed two-way valve on a tee off the test line or a three-way valve on the test line.
• 有一个可编程outpu哨兵工具t that activates during the exhaust cycle of the test. This output will active the valve to direct the exhaust out this externally mounted valve.
• 下载应用程序公告，AB138外部排气门。

• containers called the Sentinel MD instrument. Integrated onto a test stand this instrument will detect hole sizes down to 40 microns.
• Download application bulletin, AB124 Contact Lens Packaging and Sentinel MD specification sheet for more information about this process.

• First one must accept that everything leaks something over time. The leakage may be several molecules of gas per year to some higher amount. Once you accept that everything leaks, you must quantify a tolerance amount that meets the part’s functional requirements.
• Download application bulletin, AB120, How to Establish an Acceptable Leak Rate Criteria for Automated Testing.

• 将气泡测试转换为泄漏率涉及计算逃脱产品的空气量。要计算空气的体积，您必须估计气泡直径（以毫米为单位）和气泡频率（气泡/分钟）。有了这些信息，您可以使用此处的计算器。它使用以下公式来计算泄漏率。
• Leak rate = (3.14 x (dia)3 x 0.001/6) x frequency

• 在指定压力到孔尺寸的指定压力下泄漏率的转换不是一个简单的相关性。通过给定孔尺寸的流速取决于流动的状态，该流动由流体的粘度和密度控制，横跨孔的差异和出口压力与入口压力以及路径长度通过孔。
• There are several flow regimes (turbulent, laminar, and molecular) that exhibit different flow verses hole diameter relationships. In the laminar flow regime, Poiseuille’s equation can be used to approximate the hole size to leak rate relationship. At higher flow rates, flow transitions toward turbulent flow and Poiseuille’s equation predicts higher flow rates than reality. As flow transitions to molecular flow, Poiseuille’s equation predicts flow rates that are lower than reality.

• Because pressure decay and mass flow technologies work on the Ideal Gas Law (PV=nRT), variation in temperature “T” will affect the relationship of dP/dt V = dn/dt RT. The calibration function of our Sentinel instruments detects the baseline dP/dt due to changes in volume and temperature as a tare factor for future tests. As long as the changes in volume and temperature are consist, the instrument will automatically correct for the changes.
• 当在生产测试的测试时间和给定校准的测试时间内的体积或温度变化偏差时，会有可重复性或漂移问题影响测试结果。这些变化的影响百分比取决于如何进行测试敏感。
• Refer to the calculator, click here, to estimate the tolerable change in the temperature change curve and still meet a gage R&R requirement.

• Because pressure decay and mass flow technologies work on the Ideal Gas Law (PV=nRT), variation in temperature “V” will affect the relationship of dP/dt V = dn/dt RT. The calibration function of our Sentinel instruments detects the baseline dP/dt due to changes in volume and temperature as a tare factor for future tests. As long as the changes in volume and temperature are consist, the instrument will automatically correct for the changes.
• 当在生产测试的测试时间和给定校准的测试时间内的体积或温度变化偏差时，会有可重复性或漂移问题影响测试结果。这些变化的影响百分比取决于如何进行测试敏感。

• Download AB143 Derivation of Pressure Decay to Leak Rate formula.