Before the advent of discharge permits, sampling wastewater was rather casual. A can on a stick was used to collect a sample whenever it was convenient or when the boss said it had to be done. Although some cities and industries used automatic samplers for process control in the 1930s, it was not until sewer use charges became a revenue producer in the late 1950s that automatic sampling became popular. When collection of 24 hour composites became a discharge permit requirement, calling for more frequent or flow proportioned composites, a large number of new commercial automatic samplers were developed. As a result, competing manufacturers have tried to outdo each other by adding new features and complex programming. In many instances automatic sampler technology has advanced far beyond the needs and budget of the average user. Few sampling situations, for example require special features such as delayed start, asymmetrical programs or built in event recorders.
The smart operator will choose a sampler that meets his or her needs without the expense of special features that will never be used. For example to collect a sample four times an hour for a simple 24 hour composite, you do not need a complex program or elaborate key pad entry and interrogations systems. For most sampling programs the most important features of a portable sampler are light weight, rugged design and ease of set-up. The simpler the sampler, the fewer the set up errors and operating problems in the field.
Consider the following check list before you purchase to assure that you get the sampler you need and are not paying for features you don't need or want.
How often will the sampler be used?
( ) Daily, ( ) Once a week, ( ) Once a month, ( ) As needed, ( ) When storm or other event occurs ( ) Other ____________
Where will the sampler (s) be located?
( ) Indoor location, ( ) Outdoor location, ( ) Manhole, ( ) Moved by sampling crew
The Basic Sampler:
==================== Important ===== Not critical=== Not applicable
Plumbed in place:=========( ) ============( )============( )
Portable:===============( ) ============( )============( )
Size / Weight:===========( ) ============( )============( )
Fit in manhole:===========( ) ============( )============( )
Wall mount:=============( ) ============( )============( )
Lockable:===============( ) ============( )============( )
Sample Container (s)
Composite : ( )
Multi-bottle: ( )
Material:
Plastic: ( )
Glass: ( )
Interchangeable : ( )
>
Composite Capacity: (How much sample is required for the analyses?)
( ) Less than 1 gallon
( ) 1 gallon:
( ) 2 gallon:
( ) 5 gallon:
Sample Storage:
( ) Ambient ( ) Iceable ( ) Mechanical Refrigeration
Sample Inlet:
( )Vinyl (for general sampling)
( )Teflon R (for priority pollutants)
Lift from liquid to sampler ( ft.) Length of horizontal run ( ft.)
Solids handling capacity: ( ) dissolved ( ) light solids ( ) coarse solids
Power :
( ) AC (line power only)
( ) * DC (Battery Only)
( ) AC/DC (switch selected)
( ) * Internal battery
( ) * External battery
* If battery is required, don't forget a suitable battery charger.
Programming:
What type of composite is required?
Simple composite: ( )
Switch set, timer controlled sample collection frequency:
8, 4, 2 or 1 sample per hour, sample every other or every third hour.
Flow-proportioned, single composite: (paced by a flowmeter) ( )
Is a flowmeter installed ? Check manufacturer's specifications.
Type of flowmeter signal available: ( ) unpowered switch closure
( ) 4-20 ma signal
Series of composites: ( )
Multi-bottle ("one Shot") ( ) 8, ( ) 12 , ( ) 24, ( )other _______________
Multi-bottle (sequential composite) Number and volume of samples per bottle.
Inlet line purge: ( ) Before sample ( ) After sample ( ) Both (before and after sample)
(for use with battery, select sampler with choice to optimize battery life)
Method of programming:
( ) Switch select (all functions visible to operator as set)
( ) Keypad Programmable (operator input and interrogation to check selected program)
Special Functions:
Remote Turn on: Triggered by pump, float, timer or other internal or external signal ( )
Automatic turn off: ( ) When sample container is filled
( ) After preset time
With this checklist in mind, read manufacturers literature and check the features you need. Feel free to contact the manufacturers or their representatives if you have any questions or specific needs. Automatic samplers are valuable tools that are cost effective if they are simple to use and maintain and are reliable in the field.
For more information, please write
nconsys@n-con.com