Product Overview

Operating principle
The accumulation of air bubbles in
the main vent body causes the float
to drop so that the air release valve
opens. This action, and therefore
correct valve operation, is ensured
as long as the water pressure
remains under the maximum
discharge pressure.
Installation
- DISCALAIR automatic air vent 551 series must
be installed in a vertical position.
- We recommend installing a shut-off valve
upstream of the DISCALAIR vent to simplify any
maintenance operations.
- During operation the standard supplied upper
cap must be loosened in the normal version. If,
however, the alternate hygroscopic safety cap
(purchased separately) is installed, it must be
completely tightened.
- The installation of the valve in places subject to
freezing is not recommended.
- It is recommended that the standard venting
valve cap (part number 59119) be replaced by
the Caleffi hygroscopic safety cap code
R59681 in all cases where inspection is not
possible.
The hygroscopic safety vent
operating principle is based on the
properties of the cellulose fibre disks
forming the retaining cartridge.
These disks increase their volume
by 50% when they come into
contact with water, thus closing the
valve. This avoids any damage in
the event of water leakage.
Hydraulic characteristics
Discharge capacity
SCFM
0
psi (air)
15 30
456075 90 105 115 130 145
1.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
0
0.5
Maintenance
The DISCALAIR automatic air vent is designed for
easy inspection of the internal mechanism.
Access to the moving parts that control the air
outlet is obtained by simply removing the upper
cover. The body moreover can be separated from
the lower part connected to the pipe.
DISCAL
A
A
I
I
R
R
551 series
High-performance automatic air vent. 1/2” NPT female connections. Brass body and cover. PP float. Brass float guide.
Stainless steel float lever and spring. Brass air release valve stem. EPDM hydraulic seals. Water and glycol (to 50%
maximum) solutions. Temperature range 32–250°F (0–120°C). Maximum working pressure 150 psi (10 bar). Maximum
discharge pressure 150 psi (10 bar).
SPECIFICATION SUMMARIES
Construction details
High discharge pressure
The automatic air vent releases large quantities of air up to a pressure
of 150 psi, due to a large capacity internal venting mechanism.
Operating chamber
The vent body is a long chamber for the movement of the float,
which prevents any debris present in the water from reaching the
sealing seat in the automatic air release valve at the top of the
chamber.
We reserve the right to change our products and their relevant technical data, contained in this publication, at any time and without prior notice.
Caleffi North America, Inc.
3883 West Milwaukee Road / Milwaukee, WI 53208
Tel: [phone] / Fax: [phone] / www.caleffi.us
© Copyright 2009 Caleffi
CALEFFI
Code R59681
Hygroscopic safety cap. Brass body. EPDM hydraulic seals. Cellulose fibre disks seal cartridge; fiber volume increase
on contact with water 50%. Maximum working pressure 10 bar. Maximum working temperature 150 psi (10 bar).