Span Pac™ H20 Trace Moisture Gas Standard

Trace concentration moisture is an extremely important parameter in gases used in a wide range of processes. But there is no absolute analytical method that can be used in all applications. For most sensing methods, the response to moisture is affected by the background gas and most current methods are subject to “poisoning” by certain contaminants. Basically, all trace moisture sensing systems require calibration to external standards and they must be frequently challenged with standards to demonstrate continued accuracy.

There are three special problems associated with trace moisture calibration:

1. At the lowest concentration levels, there is no real zero reference point for moisture. Standards prepared by simply adding water vapor to a dry gas actually have unknown uncertainty.
   
   
2. Water interacts readily with almost all materials, so changes in pressure or temperature can appear as transient concentration changes and may take a very long time to stabilize.
   
   
3. Water is pervasive in our atmosphere, so even the most accurate standard may be contaminated in the delivery process.

The Span Pac™ H2O instrument works on a differential principal. Application of this principle is meaningful when the moisture content of the background diluent gas exceeds 10 percent of the minimum concentration to be generated. Calibration is based on the change in analyzer response caused by the addition of a known water vapor concentration from a KIN-TEK Trace Source™ water permeation tube to a flowing stream of the diluent gas. This differential method overcomes the "no zero” problem, and the problem of the background gas affecting the response.

The permeation tube emission rate is certified by the Factory traceable to NIST by gravimetric weight loss over time. This provides a close approximation to a primary standard, even in situations where primary standards are not available.

KIN-TEK takes special care in design, construction and choice of hardware components to minimize errors due to atmospheric contamination and interactions with other materials in the system.

KIN-TEK manufacturers several Span Pac™ H2O models to insure an economical solution to every moisture calibration problem.

A. Single Oven (Span Pac™ 61-H2O)

The single-oven model can produce moisture concentrations over a 20:1 range within an overall bounds of 0.1 to 10,000 ppm (depending on the permeation tube emission rate and dilution flow rate) in nitrogen and other inert background gases. The standard primary dilution mass flow rate range is 0.25 to 5 lpm. Other flow range options are available.

The component flow path features all electropolished stainless steel tubing with heat tracing.

A cabinet purge port is available to:

• Purge the cabinet with dry inert gas to minimize outboard-to-inboard contamination from atmospheric moisture when generating low moisture concentrations. Dry nitrogen or zero air is recommended.
  
  
• Maintain an acceptable nitrogen level within the cabinet when using hydrogen as the diluent gas to eliminate any possibility of an explosive mixture. The user must supply a continuous controlled flow of nitrogen to the purge port.

B. Dual oven (Span Pac™ 261-H2O)

The dual-oven model is similar to the single-oven model, but can generate concentrations over a 400:1 range depending on selection of permeation tube emission rates.

C. Single oven with Secondary Dilution (Span Pac™ 61-H2O-SD)

The single-oven instrument with secondary dilution (SD) is our most versatile moisture system (as shown in the picture above). This instrument provides both primary and secondary dilution. The secondary dilution step allows generation of extremely low concentrations over a very wide concentration range (up to 10,000:1), and generation of variable concentrations into a fixed total output flow rate.

The component flow path features all electro-polished stainless steel tubing with heat tracing.

A cabinet purge port is available to:

• Purge the cabinet with dry inert gas to minimize outboard-to-inboard contamination from atmospheric moisture when generating low moisture concentrations. Dry nitrogen or zero air is recommended.
  
  
• Maintain an acceptable nitrogen level within the cabinet when using hydrogen as the diluent gas to eliminate any possibility of an explosive mixture. The user must supply a continuous controlled flow of nitrogen to the purge port.

D. Welded Models Available for Trace Moisture Below 100 ppb

Single Oven (Span Pac™ 61-W-H20)
Single Oven with Secondary Dilution (Span Pac™ 61-W-H2O-SD)

The welded (W) instrument is required for applications that generate one or more moisture concentrations below 100 ppb. (Welded models can also be used for higher moisture concentrations.)

In single-oven models with only primary dilution (i.e., no secondary dilution), the minimum moisture concentration of 5 ppb is set by the minimum practical permeation tube emission rate and maximum allowed dilution flow rate. The secondary dilution model can generate moisture concentrations much lower.

The welded model has the same features and functions as the non-welded model including purge port and heated electro-polished stainless steel tubing. In addition, the tubing is seamless with orbitally-welded joints to further reduce the possibility of outboard-to-inboard atmospheric moisture contamination. The addition of special hardware components insures high-purity service.

E. Industrial-grade Models

All non-welded models are also available in NEMA 4 enclosures for use in industrial environments. Optional capabilities include (1) Z-purge for Class 1, Group C or D, Division II and (2) X -purge for Class 1, Group C or D, Division I.

 

Principle of Operation	Span Pac™ H20
Delivery of precise, adjustable concentrations by dilution of moisture vapor      from one or more certified water permeation tubes held at constant temperature
Models Available
Span Pac™61-H20 with single oven and primary dilution
Span Pac™261-H20 with dual ovens and primary dilution
Span Pac™ 61-H20-SD with single oven and primary and secondary dilution
Span Pac 61-W-H20 single-oven welded model for concentrations below      100 ppb (0.01 ppm)
Span Pac 61-W-H20-SD single-oven welded model with secondary dilution for      concentrations below 100 ppb (0.01 ppm)
Permeation Tube Oven
High thermal mass oven with electronic control	Horizontal orientation
Oven temperature range (heat only)	30-150 °C
NIST-traceable oven temperature
Oven temperature setpoint and display resolution	±0.1 °C
Diluent Gas (customer-supplied)
Uses inert, non-reactive, non-hazardous dry gas (nitrogen, zero air, argon, etc.)
Mass flow subsystem(s) are factory-calibrated for nitrogen diluent gas. Contact      Factory for calibration in other diluent gases.
(option) Instrument can be customized for other diluent gases such as      hydrogen or oxygen	Contact Factory
Primary Dilution Flow Subsystem
Primary dilution mass flow range	0.25 to 5 lpm
Mass flow rate accuracy	±1% FS
Mass flow rate indicated on front panel
Mass flow meter subsystem is factory-calibrated in nitrogen; contact factory      for calibration in other gases
(option) 0.5 to 10 lpm; other flow ranges available	Contact Factory
Secondary Dilution Mass Flow Subsystem (for Span Pac 61-H20-SD model)
Secondary dilution mass flow range	0.25 to 5 lpm
Secondary component split flow mass flow range	10 to 200 sccm
Mass flow rate accuracy (dilution and component flow controllers)	±1% FS
Mass flow rate indicated on front panel
Overall output gas stream dilution ratio with both primary and secondary dilution	10,000:1
(option) 5 to 100 sccm mass flow range	Contact Factory
Accepts Vapor Emissions from the Following Devices*
Disposable 0.25 in (0.635 cm) water permeation tube(s) up to 5 in (12.7 cm)      in overall length (maximum of 6 disposable tubes)
User-refillable liquid filled high rate (LFH) water permeation tube (max. 1 tube)
*Note: A single oven can hold only one of the above tube types at a time
Component Flow Path
Electro-polished and passivated stainless steel tubing to minimize adsorption
Electro-polished stainless steel permeation tube holder (for disposable-type tubes)
Heated lines
Cabinet Purge Port
Reduces outboard-to-inboard atmospheric moisture contamination
Maintains an acceptable nitrogen level within the cabinet when using hydrogen      as the diluent gas to eliminate any possibility of an explosive mixture. (The user      must supply a continuous controlled flow of nitrogen to the purge port.)
Optional Welded Models
Seamless tubing with orbitally-welded joints for Span Pac 61-W-H20 and      Span Pac 61-W-H20-SD models that generate 1 or more concentrations      below 100 ppb
Modes of Operation
Standby, zero and span modes set from the front panel
Output Concentration Range (depending on permeation tube emission rates)
Single oven model: 20 to1 concentration range within 0.01 to 10,000 ppm
Dual oven model: 400 to 1 concentration range within 0.01 to 10,000 ppm
Single oven model with secondary dilution: 10,000 to 1 concentration range      within bounds of 0.01 to 10,000 ppm
(option) Welded models for concentrations below 100 ppb (0.01 ppm)
(standard) Output gas stream can be pressurized from ambient to 40 psig for      single and dual oven models and 35 psig for secondary dilution model
(option) Other output pressure ranges available	Contact Factory
Housing Configurations
(standard) Desktop enclosure
(option) NEMA 4 enclosure for industrial environments
(option) NEMA 4 enclosure with Z-purge to meet NEC Class 1, Group C or D, Division II
(option) NEMA 4 enclosure with X-purge to adapt unit to Division I requirement
Power Requirements (specify when ordering)
115 VAC, 50/60 Hz
230 VAC, 50, 60 or 50/60 Hz
Typical Custom Applications (Please contact the Factory)
Using trace moisture with reactive gases
Using other dilution gases such as oxygen, hydrogen, CO2, etc.
Pressurized output gas stream greater than standard pressures
Other mass flow rate ranges
Your special requirements - contact us