Calibration
4-12
SVP Controller Operation Manual
Part No.: 44200004 - Revision 2
4.4 Gravimetric Water Draw
Equipment
1. Water draw kit: Contact Honeywell Enraf representative or factory
directly to obtain a water draw kit, Figure 4-6.
2. Precision electronic weigh scales of the correct size and resolution: for
example for an S25 prover, balance must have a capacity of at least
100kg and +/-4 gram (200 lb. and +/- 0.01 lb.). resolution. (1 part out
of 20,000 or better resolution). For proper scale verification prior to the
gravimetric water draw refer to API 4.9.4.
3. Certified test weight set: ANSI/ASTM Class 3 equivalent or better.
4. Source of air-free or deaerated deionized or distilled water with
approximately 38 Lpm at 172-690 kPag (10 GPM at 25-100 psig)
steady, non-fluctuating, pressure.
5. A volume catch container ideally, large enough for the volume of fluid
dispensed by the prover. Container must be designed to be placed on
the precision balance or scales.
6. Certified high resolution pressure gauge: 0-690 kPag (0-100 psig).
7. Three traceable thermometers with 0.1°C (0.2°F) graduations
(for thermometer reference positions see Figure 4-7).
8. Water draw data sheet, Table 2.
9. Water overboard container, volume to be at least as large as
test measure.
Note:
Honeywell Enraf Water Draw P&T kit or equivalent assembly eases
installation of water draw prover instrumentation. The Honeywell
Enraf Water Draw P&T kit consists of four traceable temperature
thermometers (one spare thermometer included) and one pressure
gauge. All thermometers come with the calibration certifications
if ordered from Honeywell Enraf.
Procedure
Water draw notes:
Perform steps 14 – 21 at least twice prior to taking data to purge the
system of air, assure the temperature is stable, and to get familiar with
the procedure.
Repeat water draw procedure until at least 3 consecutive draws repeat
within 0.02% or other repeatability criteria that the certifying parties agree
upon. The flow rate on at least one run must vary by 25% to assure
integrity of prover seals and absence of leakage.
Failure to achieve the necessary repeatability may be caused by leaking
valves, air in the system, varying pressure, leaking seals, or faulty
calibration technique.